It really depends on where you're going. Most national chains are not in every state, much less every city. Even when there is one in the city you're visiting, it doesn't necessarily mean it's close/convenient. I wouldn't drive 30 minutes from my hotel in an unfamiliar city just to visit a gym at which I have a membership.
Best bet is to visit an Anytime Fitness, as they do seem to be more common than others, and try it out. They'll give you a tour, maybe you can get a 1-2 free guest passes to try it out to see if it fits your needs.
My family has a Lifetime Fitness membership. I've used it a few times away from home, but not nearly common enough to do so with any sort of regularity. Mainly for working out when I'm home, for the pool facilities and child care (2 kids), and hot tub/sauna.