I noticed that about the rentals. I decided to go with a car instead of a truck, because they are so cheap relative to the trucks. And, if we all die in a head on collision, at least we were together, ya know?
What other activities did you do that you'd recommend?
The Zip Line we did was this one
http://www.congocanopy.com/enIts about 5 miles or so up a gravel road that was a bit rough in spots so if you just get a little car I suggest doing the ATV tour with it. We saw a couple of groups do it and it looked pretty fun.
We also drove to the waterfall near Bagaces. It is very beautiful but it is kinda in the middle of nowhere and there was just a parking lot, some folks selling coconut water and couple of young guys offering to guide you to the top of the waterfall for a couple of bucks.
I also went fishing on a trip I set up thru the Sheraton. Its not cheap but the pacific side of CR has some of the greatest offshore fishing in the world and it's pretty close.
I would love to take my kids and I think I would fly into San Jose, do 3 or 4 days in the rain forest doing rain forest and volcano stuff then drive over to the Pacific Coast for at least another 3 or 4 days.