I lived in Condado for 3 years. It's a nice area with a lot of restaurants, a few casinos and shops. They had a Latin Jazz concert in the Ventana del Mar park I think once a month too that was pretty cool. Downsides are a lot of the buildings are pretty old so you deal with no central air (mostly just wall units in the bedrooms), smaller living spaces, lack of some appliances like a dishwasher and you rely on the owner for repairs if renting. Make sure your place also has it's own assigned parking because many don't. You might also want to make sure the building has a generator after the long term power outage brought by the hurricane last year. There are a few more modern buildings that are fairly pricey as there is demand from investment bankers coming down from New York for the tax benefits.Â
Isla Verde is also ok if you can find a place you like down near the San Juan Hotel area. There is a grocery store nearby, casinos, restaurants, etc. If you go down the beach it's a longer hike to get to the typical stuff you need to do. The beach itself is much better in Isla Verde than Condado.Â
Otherwise there are sort of pockets of nice areas here and there, but you probably want to get some local advice. Hato Rey is the business district and has some decent housing. Miramar on the other side of the lagoon from Condado is supposed to be more or less nice, but I don't have much experience with it. Guaynabo has some nice areas, especially around San Patricio plaza from what I am told.Â
Also you may want to consider your commute. While San Juan is a small city, the traffic can get pretty snarled at times so you don't want to live on the other side of the city from where you are going during rush hour. Also there is a lot of traffic in the tourist areas on weekends in Condado at night and Old San Juan.