Santa Ana is a nice area, great weather, and very tranquilo. There are a couple nice rivers near by and I have seen monkeys fiv eminutes away from there. Traffic can be a bitch though.
Heredia, there are a few other posters over this way too. The weathers nice and all but I honestly prefer the Rhormoser/Pavas area, if I didnt have to work or had my own business that I could do from home I would probably live in Ciudad Colon, Sabanilla, or San Ramon de Tres Rios.
Looks like Avalon isn't listed here, but here is a list of the Golf and Country Clubs in Costa Rica. Guanacaste is the best area for country clubs in my opinion because of the weather.
i live in santa ana and have friends that live at Avalon. nice place but way overpriced. they live in the avalon near center of santa ana. the country club is in rio oro de santa ana. havent been in there yet. the apt. set up looks the same as the other avalon near the center.