Hotel Del Rey is safe, but staying there is a noob option. The hotel will charge you a chica fee to take a girl to your room, last time I was in CR it was $10. The post above is fear mongering....I've been to CR 58 times & never had an issue. None of the girls are pimped, pimping is illegal in CR & comes with some pretty heavy penalties. San Jose is safe during the day as long as you don't stray far off the beaten path. At night, take a taxi everywhere, it's cheap. 2000 colones will get you pretty much anywhere you need to go. As for hotels, try La Amistad, Hotel Castillo, Sportsmen's Lounge. Staying at the Del Rey is convenient, but I say it's a rookie move because girls will give you crap service when they know they can go back down & find the next sucker right away.
Key to CR is chatting with the girl a bit beforehand so you know what to expect. Learn a bit of Spanish, it will go a long way. Also, check out costaricaticas.com for more info.