You should be aware that not everyone has such over the top reviews of this place or at least consider it overpriced for what you get. I've stayed there twice as well as at several other hotels in the area and have a more mixed view. The price at Tabacon has gone WAY UP in the last few years including at both the Resort and the Springs. Most of the guys here who have stayed there probably remember it from its somewhat cheaper times (though it was never a bargain). For example, Quick Blue Fox reported getting a low season rate of just $165/nt last month and if you can really still get that rate than you should probably grab it. I just checked their REVISED website and the lowest rates that I was able to pull up was $302.61/nt PLUS tax for their "superior" rooms (which I believe are actually their lowest priced rooms). That rate was the same whether it was for high or low season AND it required a 2 night stay. Obviously that is a big difference from what QBF reported so if you're planning to go low season you might want to call them direct and see what sort of rate you really can get. At this point with high season beginning and the place starting to book up, I'd be surprised if you'd still be able to get those lower rates.
You didn't say how you were planning to get to the Arenal area, what you planned to do there (other than Phuck your "novias"), what your budget was and it wasn't clear whether you really meant to stay their 2 days and 1 night or 3 days and 2 nights. All those things would factor into the equation before I rushed off on recommending this place FOR YOU.
Are you planning to rent a car and driving there. Some guys hate driving in CR. I actually love it and DEPENDING on what route you go, the drive out to the Arenal area can be quite pleasant. Also, once you're there, things in the Arenal area can be quite spread out, probably necessitating taking a lot of cabs depending on where you stay if you don't have a car. There are seperate threads on the various ways to get to the Arenal area which I encourage you to look up. The reason I brought it up now is because, if you're planning to have your own car AND you're hoping for LAVA views at night from your hotel room, you should know that the lava flow has shifted around to the opposite side of the volcano than where it might have been when these other guys stayed at Tabacon. Your best chance of being able to see the glowing lava from your hotel room now comes if you stay at a hotel that is further out (hence the need for a car). Your best bets for such hotels would probably be either the Arenal Lodge
http://www.arenallodge.com (w/volcano view rooms starting at $110/nt) which I have also stayed at, or the more luxurious Lost Iquana Resort (w/rooms starting at $185). Another often recommended hotel is the Arenal Observatory Lodge
http://www.arenalobservatorylodge.com. They're actually the hotel that is closest to the volcano and the absolute best views and they have rooms ranging from the very cheap to the very expensive (depending on how much luxury you require, etc). However, this place is really out there and requires a really long drive all the way around the volcano. There are also really cheap places located in the area of the village of El Castillo that also are positioned for good lava views but which are even further away from both the volcano and the rest of the Fortuna area attractions and thus are probably not recommended for you.
How many NIGHTS were you planning on staying there AND were you planning on spending a lot of time just at the TABACON Hot Springs BOTH days you were there? IMHO, the only thing that makes the Tabacon Resort semi-reasonable in price is the fact that admission to their hot springs is included with your stay. That was recently priced at $60 per person per day if you were staying someplace else and purchased them seperately. Their website now only offers passes with their overpriced meals ($70 for their 4 hour evening pass w/dinner, $85 for their unlimited pass with lunch and $95 for their unlimited pass with both meals). So if you accept those values and both you and your novia plan to use the hot springs, the "net cost" of your room drops by $120. Perhaps not coincidentally, that brings it down to about the same as Lost Iguana, which is probably similar in terms of luxuriousness but which is better positioned for night time views of the lava. HOWEVER, Tabacon ALSO requires a 2 night stay minimum. Even if you plan to stay for 2 nights anyway, would you also be planning to use their hot springs (for $60 worth) both days you were there or would you check out one of the other much cheaper but also very nice hot springs in the area for one or both of those days or even not spend very much time in the hot springs for one of those days and spend more of your time participating in one or more of the many other activities available in the area? If you really would only have otherwise spent $60/pp for one of those 2 days then your "net cost" of your room at Tabacon really only drops by $60/nt ($302/nt x 2 nts - $60/pp for 1 day @ the springs X 2 people = $484 or $242/nt). Tabacon is certainly very nice but at $242/nt other very nice places start to look like much better values.
The important point to realize is that while the hotel is very nice, what really drives everybody gahgah about this place are the hot springs AND you don't HAVE to stay at Tabacon to visit them. Also, while their hot springs are very nice, there are also several other hot springs that are nearly as nice (or in some people's views nicer because they are less touristy) and which cost only half as much or even less. IMHO, Tabacon is probably worth its exorbitant price to visit at least once, just to see what all the fuss is about if nothing else. However, if I were staying in the area for 2 days or more, I probably wouldn't pay $60 to go back the 2nd day opting instead for either a different hot spring and/or some other activity such as ziplines, canopy bridge, canyoning, waterfall, horseback riding, rafting, volcano hike, ATV etc. then maybe go to one of the other hotsprings to soak for a couple of hours afterwards for $25 or less.
Yet another hotel that I've stayed at in the area is Los Lagos
http://www.hotelloslagos.com. It has gotten a lot of very good reviews from many guys here at CRT but like Tabacon has seen its rates climb quite a bit as well. Currently, it has rates ranging from ~$95/nt for their standard rooms low season to ~$150/nt for their superior rooms high season ($110-174 INCL taxes). They are not quite as luxurious as Tabacon but are certainly very nice and perhaps more within your budget. There are also places even more affordable than that which of course come with a certain trade-down in comfort but which are still perfectly fine places to stay. For more info on many of these places as well as general info on the Arenal area, activities, tours, etc. I recommend you visit
http://www.arenal.net