So far, there are three proposals for the redevelopment of the crucial commercial block of Pennsylvania Avenue:

A work of Miami Beach-style architecture.

A sensible commercial building.

A varied link between the Willard Hotel and the National Theater.

These and any further porposals that may come along will be presented to the Pennsylvania Avenue Development Corp. on July 31. The corporation, an independent federal agency which set careful criteria for this competition, will take until September or October to examine the entries from the esthetic, urbanistic, financial and traffic points of view.

One of the most important concerns is the future of the National Theater, the capital's oldest existing playhouse which, since 1835, has occupied six successive buildings on the contested site.

The jazzy, Miami-style scheme, designed by architect-developer John Portman on behalf of himself and the National Press Club, would force the theater to relocate.

In a rather high-handed manner, the Portman-Press Club combine has announced that incorporating the theater in its scheme would be too expensive. It handed the National Theater board of directors and the press a sketch for a new and utterly inappropriate theater building. No one has any idea where the land or money for it would come from. Noisy Portman-Press Club publicity can surely not produce it.

The corporation said clearly that it has no plans at present, to provide a new site for the theater. Roy Harris, counsel to the theater's board of directors, said: "Portman might as well propose to tear down the White House and put a new theater in its place."

But Portman-Press Club publicity persisted, apparently calculated to create the impression that the combine was to build a new theater and that its proposal for the block was the one and only solution.

All three proposals encompass Square 254, the block between 14th and 13th and E and F streets, except for 1301 Pennsylvania Ave., a new office building for which ground has just been broken. In addition to the national Theater, the block includes the present National Press Club Building.

The sensible commercial proposal was designed by architects Weihe, Black, Jeffries & Strassman on behalf of the John Akridge Co. Weihe, Black, etc. is a local firm which has designed numerous office buildings around town of which this is unquestionably the best. Akridge are young, up-and-coming developers.

The Akridge scheme is to be built in stages, letting the present, recently refurbished National Theater operate until a new one is built inside the block. It would still have an entrance way from Pennsylvania Avenue.

"A theater doesn't need windows," said John E. Akridge, "but a desirable office does. That's why, in a later phase of construction, we would build a new auditorium and stage house in the interior of the complex, adjacent to a shopping mall. It would be already before we tear the old one down to replace it with offices fronting on the avenue. We think we can coordinate construction so that the theater would not be dark for a single night."

The third proposal, designed by Frank Schlesinger and Mitchell/Giurgola for the Quadrangle and Marriott Corporations would leave the National Theater permanently untouched. The design, in fact, emphasizes the present theater facade, built in 1923. It is less than an architectural smash hit, but has a pleasant aura of tradition and respectability about it.

The National Theater board of directors endorsed both the Akridge and Quadrangle/Marriott proposals. Harris said it would have to be seen whether the theater prefers a new building with improved loading and storage facilities) or retaining the old one. "That's a long wy off," he said. "What counts is that we keep our 143-year-old address and that we don't have to close down for years."

All three proposals will provide a somewhat similar combination between lively interior malls with shops, cafes and restaurants, offices, and a hotel. A hotel is essential to assure that Pennsylvania Avenue stays lively after the government offices in the Federal Triangle close at night and on weekends.

Portman and the Press Club offer a 1,066-room convention hotel, with ballrooms, bars, lounges, 600,000 square fet of rentable office space, 35,000 square feet of Press Club space, as well sa shops, all jumbled into the kind of soaring salesmen's paradise that has made John Portman famous in Atlanta, Chicago, San Francisco and Detroit.

Architecturally, the Washington Portman is ingenious, presenting not one, but four interior courts, with sky-lights all interconnected, to give us one fun-filled combined super lobby supermarket. Perhaps there is room in Washington for the somewhat vulgar vitality these Portman spaces generate. There is no question that they draw big crowds. In addition to the unacceptable sacrifice of the National Theater there are, however, several severe flaws in the proposal.

The worst of them is that Portman's skylight attractions add nothing to Pennsylvania Avenue but an unattractive facade. On the outside the building is essentially a glass box with massive concrete towers on each corner. It is adorned with greenery. Portman forgot that during our winters nature will refuse to help his architecture.

But the climate is no execuse to encapsule all attractions inside as in a fortress. The glass and greenery do not overcome the impression that this is an exclusive enclave for the credit-card crowd who would have nothing to do with the city. The design has no more empathy with Pennsylvania Avenue and what it stands for than the FBI Building or Miami's Fontainebleau.

What is more, Portman and the Press Club want several zoning variances to make their building larger and more profitable.

The Akridge proposal, in contrast, shows understanding for the "grand avenue" and its problems. It is primarily an office building above a big, wide-open shopping mall, leaving the new theater and perhaps a small (200- to 300-room) hotel for the future.

The three-level enclosed mall and the stores along the avenue (technically E Street, but never mind), would be developed by the Rouse Co., the maestro of American shopping centers. Rouse's latest triumph is the enormously successful Quincy Hall Market in Boston.

The Akridge-Rouse Mall, as presently envisioned, is also largely festive, with skylights, but in a more conventional and less exclusive way than Portman's. Like the Galleria in Milan, it is an enclosed part of the street scene. You can use it as a shortcut between F Street and the avenue.

Architect Byron B. Black's facade, broken up by rythmic notches with balconies (the better to view the inaugural parades), is pleasantly neutral, in the way the buildings on the Champs Elysees in Paris are neutral and do not detract from the bustle of the street. What I like most about the building is its respectful bow toward the old Willard Hotel, across 14th Street, soon to be restored to its palatial glory. The Akridge scheme includes a plaza on the 14th Street corner that gives prominence to the Willard.

What I like less about the building is that, like Portman's, it is a block-buster - notches, recesses, arcades or not, it is a huge monolith.

The greast virture of the third, the Quadrangle/Marriott scheme is that it is not monolithic. It is what good urban design should be, not an edifice unto itself but a continuum of the existing cityscape; not an architectural statement, but a new voice in the avenue's conversation.

It is also a big hotel, a Marriott convention hotel that will initially offer 850 rooms, to be expanded to 1,400 rooms, ballrooms, exhibit halls and all the rest. There will be 100,000 square feet of retail and 450,000 square feet of office space.

But all this, as architect Schlesinger put it, is "placed gently on its site." The massive bulk of the building is along 14th Street. What you see along the avenue is a building that appears to be of the same height as the National Theater. The actual 16-story height is set back from the avenue in two steps and will not be apparent from the street.

What will be apparent is a shopping arcade and three stories of restaurants enclosed by curved glass that lend interest to the facade. The hotel and the offices are clearly expressed on the outside of the building to give it variety.

The interior shopping concourse is to include an ice skating rink and is linked with that of the Quadrangle building on the 13th Street corner which also was designed by Frank Schlesinger.

(Mitchell/Girurgola, who work with him, is a nationally prominent Philadelphia-based firm.) Another asset of this proposal is a sizable automobile and bus garage entrance and drop-off on 14th Street that should help reduce traffic congestion on street and avenue.

All three schemes will still have to work out such all-important esthetic details as materials and color, to say nothing of the economic arithmetic.

All three, however, are cause for jubilation. They show serious business interest in Pennsylvania Avenue and the heart of our city. They also show a cosmopolitan sophistication the absence of which has driven people to White Flint and Tysons Corner.