EVEN ITS FONDEST boosters admit that Silver Spring, Maryland's largest unincorporated city, is not long on looks these days. The decade since Silver Spring last flourished as a modern shopping center has been harsh, leaving blocks of dingy old discount shops along Georgia Avenue and Colesville Road, a generous share of litter and an image that the Chamber of Commerce has been hard-pressed to shake. The great hope was the opening of the subway station, but that alone hasn't been enough; passengers come and go easily without pausing in the grim commercial strips.

Yet there are some welcome signs of new life around the station, stirred by businesses that recognize the development opportunities that have been opened up by the subway system in other commercial areas in the region. A large hotel chain is planning a 500-room hotel near the station, complete with what are being billed as the largest conference facilities in the area; at least two office buildings are schedueld to go up in the vicinity; and a large department store chain reportedly is considering opening a branch.

No one is sure whether these reports are what have prompted plans for still other renewal projects -- including new sidewalks, trees, parks, markets, murals and waterfalls -- or whether it is the other way around. But the movement is picking up as some owners of existing stores have begun promotions aimed at subway riders. Silver Spring may not reemerge immediately to rival the big new malls elsewhere in Montgomery County, the new-old attractions in Alexandria or the shopping complexes being built in downtown Washington. But in the future, some of the most attractive and logical sites for commercial development in the region should be in and around the subway stations.