A thermal spa package pertains to an area of a spa with pay-for limited access to whirlpools, soaking tubs, high oxygenation pools, heated tile benches, cold rooms, plunge pools, hot tubs, aromatherapy showers, saunas, high pressure water jets, etc. Few ships have well-designed facilities, others offer only a couple features or else cram the facility into less than relaxing spaces. 

What has been your experience with thermal suites? Is this a regular part of your cruise experience?  Plusses.... minuses?