Htoad,
Yes, there are ATMs all over San Jose, and most will work with your ATM card without problems. Look for the Plus+, Cirrus or Redbank symbol on the machine, depending on which system your bank uses.
Some banks charge fairly excessive transaction fees to use ATMs.
Here's a very limited list of ATMs I've used in San Jose:
Banco de Costa Rica, both the c. 7/av.1 branch and the one on Av. Central. No problems, ever.
Hotel del Rey casino: One machine dispenses colones, the other U.S. currency. I've used both, no problems.
Colonial Casino. Two ATM's. One near the main cashier's cage dispenses a ticket rather than cash, which you take to the cajera to get your money. This is convenient if you want cash in denominations other than the 10,000 colones bills dispensed by other ATMs. The other ATM at the Colonial dispenses cash. The one near the cashier's cage had problems last time I tried it, but the other machine worked fine.
I always carry cash to C.R. and don't use the ATMs unless/until I run out of what I've brought. Remember to bring only fresh, unmarked, undamaged U.S. currency. The bills must appear fresh and "perfect," or they will not be accepted.
Hint: Buy a money belt/leg wallet/chest wallet for carrying your cash. Be sure to lock up whatever you don't need to spend during an evening or daytime outing; even with a "hidden wallet," don't carry all your cash on your person.
Hope this helps. Oh BTW...forget travelers' cheques. Pretty worthless in C.R.
