Some 15,000 real estate professionals who came here this week to meet and play plumped some much-needed revenue into the once-posh hotels along this city's ever-narrowing beachfront.

While they were in town, members and convention-followers of the National Association of Realtors got a chance to marvel at the growth of condominium apartment living along Collins Avenue, the opulence (some of it now a bit tarnished) of homes along the waterways and the increasing presence of Latin Americans in the south Florida area.

Realtors who stayed at the newly opened Omni Hotel - commercial complex in downtown Miami got a glimpse of what may be a prime example of a new type of inner-city commercial revitalization - an enclave of hotel rooms, meeting space and shops. The 10.5 acre complex cost about $78 million and has Jordan Marsh and J. C. Penney as anchor stores in the shopping area. The hotel has 556 moderately priced, fairly small rooms that are comfortable without being posh.

In appraising the current residential housing market in south Florida, consultant Lewis Goodkin said that a "moderately strong" upturn in the sales of both single-family houses and apartment condominiums can be attributed to a continuing influx of snow-escaping, mature adults from northern states and Canada. Moves here by affluent residents of Cuba and an increasing number of South Americans who have come here to invest or relocate also have added to the upturn, he said.

Goodkin, who keeps in close touch with the housing market here, commented that the strongest residential demand is for single-family houses priced around $35,000. But he added that the desire to move up to something bigger and better is also evident. People who moved here to apartments are now tending to parlay their equity and higher incomes into houses in golf course communities further out in Broward and palm Beach counties, he said.

In southern Palm Beach County, about 50 miles north of Miami, Arvida Corp., which had its genesis with early Florida developer Arthur Vining Davis, has been attracting young and older families.

Because new construction has been inhibited by local authorities in Boca Raton, site of one of the first of Florida's recreation hotel complexes, Arvida in recent years has been developing a new community called Boca West. Many of the houses there cost around $100,000 and a few are priced in the $400,000s. Boca West has three golf courses in operation and a fourth under construction. Most of the apartments and town houses are located near tha fairways.

The development trend for golf-oriented communities has been to build five detached but closely grouped houses to an acre, with little or no space between two adjoining units. Goodkin said this usually means 18 to 20 houses are built near each golf hole, minimizing the cost of finished lots, which usually average more than $12,000 in low-density, multi-family developments.

The housing market in the Boca area got a lift with the location of an IBM employment center and some other non-industrial, service industries.

"But the biggest overall market for new dwellings, including everything from small singles to garden apartments and upper-grade mobile or manufactured homes, is still around $35,000 in south Florida and fast-developing areas in more central areas of the state," Goodkin noted.

Goodkin and others agreed that much of the unsold inventory of condominiums, which were heavily overbuilt a few years ago, has been sold off as a result of price cutting and a surge of buyers seeking bargains.