It used to be that if hotel health & leisure facilities existed - they'd be an old bike and a tatty swimming pool! These days, however, hotel health & leisure facilities have woken up to the fact that their guests want a decent place to work out - indeed, some hotels have such good facilities that they are open to non-guests, just like any other health club.
A modern hotel gym should be as well equipped as a regular health club. You should expect to find a decent range of cardio equipment, some free weights, a pool, and maybe even a studio for classes.
In the cardiovascular area, you should find the same up-to-the-minute CV equipment as in a regular gym, with Cross Trainers, Steppers, Treadmills, Rowing Machines and Stationary Bikes. The weights area should have a mix of resistance equipment and free weights. Many hotels now employ qualified fitness instructors, and can thus offer both fitness assessments and personal training.
Health suites are common, offering you the chance to relax in a sauna or steam room, or be pampered by the hairdressers and beauticians. Health suites are a designed for relaxation and improved wellbeing, just the place to go after a workout or a stressful day. Many will also offer sun beds.
Use of the facilities should be complimentary to guests, though beauty treatments would be extra. It is also worth considering private membership of a local hotel gym - in addition to offering competitive rates, many also offer 24 hour access.