I agree, that in some hotels the workout rooms are not really that good. But to me, every workout room / gym / fitness center is better than not doing some exercises. And there are enough cities, where I would not doing running outside (e.g. Newark
, Phoenix in Mid August ). From my experiences, the workout rooms are not that crowded in the early morning, while beetween 18.00 and 21.00 they are sometimes pretty full.