TTA for sure in MK. Maybe the train, but if I'm in need of rest AND cool air, TTA creates a much better breeze. Train stops too much. Plus, the train is a tad bumpy and jerky if I need to get rid of a head ache.
LWTL for sure at Epcot. Especially now that there's no CM on board. The new voiceover is soothing. France always provides a nice cool place to recline and nod off too.
I can't think of anything that's relaxing, per se, at the Studios. Maybe VotLM, but I enjoy it too much to relax or sleep.
I don't spend enough time in AK to find a place to relax....