As a fitness trainer I would like to interject; if you don't mind.
Number one important criterion, is the location convenient? If it is out of the way then you are less likely to go. As a gym member I love folks who live 10 miles away from our facility and join our club in January thinking its not that far. Today you cant get on a machine and have a hard time finding a pair of dumbbells. In six weeks you will hear crickets again. But they are still paying membership fees; keeping my fees low.
Next, what is you experience level? If you are a rookie and have no experience you want to gym home to have QUALIFIED folks there to assist you. For your safety you need to understand form so a qualify fitness person should be there for help if you are a newbie. Ask about qualifications of staff on the fitness floor at any club you join.
What do you want to achieve? If you are currently fit and just looking to maintain then any facility will work. I have a room at the house that is where I work out is small intimate and I do not get interrupted like I do at the club. If you are just starting I think you are looking more at a full service club. You really want to engage a trainer for 6-8 weeks just to get you started. Sure all clubs will give you the 30 minute once through on equipment but the next time you walk in the door will you remember those really little subtle points like head up, back straight, breath? These guys will help get you going and be there to motivate you, listen to you and help get you past that inevitable plateau that will occur in mid Feb.
A bare bone place where is totally useless is you do not understand what you need to do. You will quickly fall into the trap of going to your favorite couple of machines, never pushing yourself and then wonder why you see no change. If you have some experience then a bare bones place works great better than many clubs due to the fewer folks.
I think the curves assessment is not too far off. It is a start but my DW quit after 3 weeks as the local one was more of a social club.
Where ever you end up just make sure that it is a clean and safe place. Look at the facilities as you tour. Are the machines clean, showers clean, toilets clean? Does the staff look professional? Are there a variety of members? Not to sound cruel, but you really want to see fit folks, a few muscle bound folks and then de-conditioned folks. A club with a population that reflects your community will feel more like home. You will be more likely to keep going. If you talk with the folks who look fit you will find that some of these folks were in the de-conditioned population earlier.
Hope this helps. I know I did not validate the choice but this is really what you need to look at and assess as you decide where to spend you hard earned funds.