During the day, the Horseshoe is your best bet. They start at 3:30 daily. There is usually a nice turnout early as they have promotions for players that buy-in before 4pm.
At night, the Del Rey poker room has 3 tables going, it was pretty good in last month. They usually play 1/2 and 2/5.
Clarion Amon Plaza and Colonial also have poker but they were dead when I went in August.
Hotel Ramada Herradura (10km from downtown, on the highway to the airport) is the new higher limit place to play in San Jose. They tournaments too. Here is a series of tournaments they are holding next month:
http://pokerhispano.com/torneos-de-poke ... ca-71.html
But if you're looking for the 1/2 game, you should stick to Horseshoe and HDR.