Is there anything like a Priority Pass for gyms -- a card that you pay for which gives you access to a variety of gyms on a PAYG or monthly basis (assuming you are say more than 50 miles from home base)? I remember years ago that there were these gym roaming affiliations where you could take your club card from NJ gym A and use it in FL gym B.

I know you can buy day passes to gyms, but you are often stalked by personal trainers and sales people and it usually means taking 20 minutes to get in instead of just walking in. This is sort of what I am describing:

http://www.gymclub.com

but it is only for gyms on the Isle of Jersey. I guess this would be valuable if I wandered to different parts of the Isle and was too tired to travel back to the part of Jersey where I lived. (As I recall, the island was something like 25 miles big).

I think the "roaming affiliations" still exist to some extent - http://www.healthclubs.com/passport/

I tried finding this a few years ago when my travelling was at is peak. I did not find anything that would work for me. It always seemed like the affiliated clubs were really inconvenient for where I was working/staying, if there were any at all.

Many of better hotels have an affiliation with a nearby health club/gym. Basically the concierge or front desk would arrange for a day pass or week pass (usually at some cost). That worked for me in some places. Maybe that would work for you.

"The chain operates in 48 of the United States, plus Canada, Mexico, India, United Kingdom, New Zealand and Australia"

http://www.snapfitness.com

A buddy of mine has a membership, and uses it all the time when he travels (membership is valid in every location).

Planet Fitness's $20/month plan allows you to use any of their gyms.