you might want to look at the option of flying night before SLC/ATL and getting cheap room (Comfort Inn North--ask for DL employee rate 404-768-7800) and take on of the early flights ATL/SJU--wide open!
worth the extra $60 to almost guarantee first class (9:51 and 10:55 have oodles of front seats)
you get there much earlier (beach time!!)
local buses are really cheap
free stuff--2 forts in old san juan--really great walkaround
get a guidebook from your library
haven't done the rainforest but I'm sure you can take bus and see w/out buying tour--just pay admission
Metropol restaurant is great food--cheap--local (Condado/Isla Verde area)--also Mi Casita
I'm sure you'll get lots more info soon