My wife and I stayed for 3 nights at Arenal Green. They have small but roomy cabins with view of the volcano (when not covered by clouds). First let me say this Monica is a gem! She runs the front desk and is extremely helpful! She helped us greatly with tours and transportation and lots of general questions. The hotel is about 25 minute walk to La Fortuna town and about 30-35 minute walk mainly uphill to the La Fortuna waterfall.
We stayed in Cabin eight which is very nice for couples. There are basic necessities including a sink and fridge. The shower is spacious and there is ample air conditioning. The bed however is a little hard but thats ok. Every morning at least one rooster crows about 5-5:30 which lets you know its time to wake up. I found it kind of amusing since I own chickens myself but they aren't quite so ambitious.
The grounds are manicured and there are lots of hummingbirds in the area around a couple bushes mostly. We also were delighted to find a pineapple plant growing next to our cabin. Also there is a creek/stream with a path to the back of the property.
Breakfast is fantastic with two choices of traditional or american (with bacon...yum), served every morning. Oh yeah, WI-FI signal was basically non-existent in our Cabin, but once in the lobby area was great of course. All in all a nice place for a reasonable price.