Hi,
We stayed at the Arenal Paraiso last month. It was perfectly fine. The rooms are all private cabins and our AC worked well. I believe we payed around $100 per night (July is low season so I assume it's more in the high season). It has its own hot springs and it even has its own zip line tour.
Drinks at the swim up bar were $7 for cocktails and $4 for beer. The restaurant was quite good as well, however, it was a bit expensive. Unless you have a car plan on having at least a few meals there.
There were several other hot springs resorts nearby. A friend of mine is at the Springs right now and she loves it. Los Lagos was also close by. I had been to Tabacon several years ago and thought it was a bit touristy and overpriced.
One other thing, unless you're going in the dry season there's a very good chance you won't actually see the volcano. We only saw the base in the 3 days we were there, but we knew it was a possibility so we weren't that disappointed.
Hope this helps. We really enjoyed Costa Rica.
Tim