I don't know jack about Guatemala (it's somewhere near Des Moines, right?), I can say that Costa Rica is a blast.  I'm told the fishing there is great (can't say first-hand, I don't fish), and the nightlife in San Jose is great.  But you probably already know that, since you're already considering a trip there, so I'll stop the cheerleading.
   Anyway, if you're looking on info on CR, hit the link below.  There's a lot of great guys who have forgotten more about Costa Rica than I will ever know on the boards, and a little time searching through the archives will yield plenty regarding hotels, activities, restaurants, and I think there was even a post about laundromats a little while ago.  Best of luck!

PapaJester

P.S. - I'll be travelling down there a couple times this winter.  PM me if you decide to go, and if I'm around when you get there, I'll buy you a beer.