I'm biased - the Juan is one of my favorite places. So I vote for it, too.
February will be warmer than now, for sure. A co-worker friend of mine who's an expert (at least in my estimation) on the river says that if the temperature's above 40 and the sun's out, he's comfortable there. Lower temps and/or no sun, not so much. But he also says that he's a fair-weather fisherman nowadays. You're likely to see that kind of weather, but there will be periodic storms rolling through with (hopefully) precipitation, usually snow or mixed snow/rain. See
for what the fishing's like in that sort of weather. The guy with the net, by the way, is Chip Hodlmair. He's a great guide and I highly recommend him; took me on my first float down the river. The first fish of that day is in my profile picture.
I'll second the opinion that there's not much to do in the closest cities in NM (Bloomfield, Aztec and Farmington). However, Durango is an easy hour drive away. Good restaurants (I've eaten at Ken and Sue's, The Cosmopolitan and Seasons and can recommend), nice assortment of hotels, some nightlife, etc. It's a tourist town for sure. 25 miles north of Durango there's skiing at Purgatory. Not the most challenging mountain in the area (go to Silverton Mountain, Telluride or Taos for that), but it's fun especially after big dumps. If you're into casinos, the Southern Ute tribe has a big one, with hotel etc., in Ignacio - that's less than 30 minutes away from the Juan in good weather.
If you're interested in the river, I'd recommend the San Juan River Forum. Lots of experience and good advice.