Montgomery County planners, promising shimmering office and hotel towers, have tapped half a dozen projects for top ranking among developments competing for coveted zoning in the blocks surrounding Bethesda's Metro subway station, which is scheduled to open late next year.

The rankings, if approved in the coming months by the county's planning board and the County Council, will give developers of selected projects exclusive access to build, and will determine the face of downtown Bethesda's choicest commercial zone.

With the approval of the County Council, the county's professional planners chose to approve all the projects at once, rather than in the usual piecemeal pattern, in hopes of producing a compatible end product. The planners also want to limit the number of projects--in what has been called the most pressure-packed suburban redevelopment area in metropolitan Washington since Rossyln and Crystal City--because of concerns about the additional traffic they will generate. The biggest proposed project, known as the Woodmont Air Rights Building, was among three not recommended.

Donald Downing, planning coordinator for southern Montgomery County, said he expects the planning board to finish its review of the staff recommendations by July; the plan then goes to the County Council for approval. The planning board is scheduled to begin its review June 22, he said.

The planning staff's long-anticipated selections, released in a staff report this week, cap what came to be known as Bethesda's "beauty pageant" of architectural designs, and is the crucial point of the controversial one-shot zoning approval believed to be the first of its kind in the nation. Developers were required to submit detailed plans not normally required until advanced stages, after development is approved, at a cost of hundreds of thousands of dollars and with no guarantee of approval.

The special zoning process was conceived by John Westbrook, a former Rouse Co. official who is chief of the county's urban design division. He intended it to extract from developers the most extensive public amenities possible.

In addition to office buildings and hotels, the competition produced statues, botanical gardens, wall murals, skating rinks and waterfalls in unusually expansive public areas.

The projects designated for preferential zoning treatment are in addition to a $160 million development by Rozansky & Kay already under construction at the entrance to the Metro station.

That project, known as Bethesda Metro Center, will include a 17-story Hyatt Regency Hotel, offices and a shopping arcade.

It is believed to be the largest private construction project in the county's history and is scheduled for completion in February 1985.

Both planners and developers said the idea of making individual applicants compete for zoning approval is likely to be challenged in court by losing developers.

The winners, in order of choice, were:

* Chevy Chase Garden Plaza, an office and residential complex of cascading building heights from eight stories proposed for a triangular block bordered by Old Georgetown Road, Moorland Lane and Arlington Boulevard. Planners said the 200,000-square foot office and town house complex, to be developed by Chevy Chase Savings & Loan Association, would "provide a very wide range of opportunity for public enjoyment" with such features as waterfalls, gardens, a lily pond and "personal and intimate places" where people could "enjoy the peace and quiet of being in a very enriched environment."

* The Artery Organization Building, on the northwest corner of Wisconsin and Bethesda avenues, would be a 400,000 square foot, 14-story X-shaped office tower, with street-level shops, to be built next to the existing Government Services Savings and Loan building.

Another 14-story building proposed for 7475 Wisconsin Avenue would feature an escalator connecting to the underground rail station. The 150,000 square foot building would be developed by Perpetual Savings and Loan Corp. with JBG Associates.

* The Gateway Building, at the northeast corner of Wisconsin Avenue and Willow Lane, would be a six-story pink office structure featuring the Willow Garden Theatre. The staff commended the developer, the Burka family, for retaining Lowen's Toy Store, calling it an "important community resource."

* A 12-story, 150,000-square foot office building would be built adjacent to Shakey's Pizza at 4600 East-West Highway, at the southeast corner of East West and Wisconsin. The developer, JBG Associates, agreed to include and support a community art gallery in the project.

* Another project likely to be approved, Downing said, is the Air Rights Hotel. Although the 14-story structure at the southeast corner of Wisconsin and Montgomery avenues was ranked eighth by the planners, Downing said it could win approval ahead of the sixth and seventh ranked projects because they depended on extension of Woodmont Avenue. Last month the County Council eliminated design and planning money for the extension.