I never bring in more $ than what I'll need to get home from the airport when I return to the US and maybe get some food.
As soon as I arrive in CR, I go to one of the ATM's in the baggage claim area and take out about ¢200,000 colones (~$360 at today's rate) that will last me for the first couple of days. Then as needed, I just hit the ATM and take out local currency.
Why?
1. Like mentioned before, the lines to exchange money at the banks are not usually long but slow as Phuck. Plus, I don't like to be frisked and wanded like a friggin criminal each time I enter a bank and have to remove my sunglasses and cap.
2. I don't trust the hotel safes. And more importantly, I don't trust the hotel employees. To be fair, I have stayed in probably 80% of the hotels in the gulch, and have never experienced theft by any hotel staff. But I still wouldn't want to give them a chance to steal much cash from me.
3. I don't like carrying much cash on me. You can lose it or you can be robbed (although chances are slim you will be robbed on the way from airport to your hotel in a taxi; I said slim, I didn't say zero.

Remember the taxis that were being stopped and robbed on the highway from the airport a few years ago. The cops put a stop to that quickly after the info started appearing on travel boards.)
4. If you exchange somewhere other than a bank, you are gonna take a hit. 2 weeks ago, Del Rey was paying 515 when the rate was 552. That's 7%. Expect 5-10% hit. 2-3% is a convenience charge, but 7% is high.
If you do exchange at your bank at home, ask and compare the rate ahead of time. I have NEVER heard of a US bank giving a fair exchange rate. What they waive in the fee, they more thna make up for in the rate.
National Bank website has the "official" rate in the upper right corner:
http://www.bncr.fi.cr/BNCR/Default.aspxToday, they are paying 541 colones per dollar. When you are leaving, they will sell you back dollars at 556 colones per dollar. The spread is usually about 10-15 colones, so you are losing 2-3% if you try to exchange colones back to dollars, so don't exchange too many dollars or take out too many colones that you have to convert back into dollars.
Another tip: DON'T FORGET YOUR phucking ATM CARD WHEN DONE WITHDRAWING MONEY. After a thousand withdrawals, I finally left my ATM card in the machine and walked out. I blame my friend, he kept talking to me. Nothing happened. It's a travel account so I keep a few hundred in there and ATM's in CR make you re-enter the PIN for another transaction. They take ATM security seriously there. BTW- ATM's shut down each night at 10pm and don't come back on until the next morning, so plan accordingly if you plan to pick up, or have, a "date" late.