I stayed at Xandari Resort & Spa in Alajuela, wouldn't recommend it.
Arco Iris Lodge in Monteverde was amazing, highly recommended to anyone.
Lapa Rios met my expectations, terrific!
I'm not sure if Bosque del Cabo is better, I was surprised when they dropped me off for a hike at Lapa Rios on the way we passed Bosque del Cabo! About... 7 min. drive up the road.
Santa Elena/Monteverde didn't have much to do, I loved it up there though!
Skip Aventura Canopy ride, it wasn't safe. Selvatura was amazing and fun and the guys that worked there were soooo friendly! (in Monteverde)
Hire a driver if you aren't familiar with the roads, I only saw 2 signs the whole time I was there.
Make sure you are going to Corcovado on a day it's not too hot. I went on a hot day and saw very few animals than I expected.
NatureAir was great.
I didn't get any mosquito bites, only tick, and spider bites and a jellyfish sting.
If you would like my itinerary, post here. Everything I planned turned out as I wanted and I planned EVERYTHING over the internet!
Feel free to add comments/suggestions.