I've used a few strategies back in the days when I was still racing (and therefore wanted to have some fitness) but also in hotels for, often, 5 nights a week. It's much easier if you're in the same hotel for some weeks.
I've taken a turbo trainer and a bike - hotels often have a conference room or, if all else fails, a car park where you can set up. Just develop a thick skin about passers-by. Usually though I found that they are interested really, and a chat whilst on the turbo can relieve some of the boredom.
Local gyms are often interested to negociate a temporary membership for spin etc. I've found that the 1st line dask staff may not see the possibilities, but if you ask to chat to the manager they can usually come up with something. A good spin (sorry!) - off is that you may meet a few people and make some (albeit temporary) friends.
My advice to anyone working out of hotels for any length of time is to "live where you are staying", in other words find places to go, theatres, gigs, bars, cycling clubs or whatever you might do at home, and develop a life there rather than work/hotel restaurant/bar/bed.