We prefer the transit hotels, they charge min 6hr block and then hourly after that.

I prefer T1 as its quite/more cave like, I found some of the rooms at T3 can be noisy and I can hear PA announcements and golf carts beeping.

Lots to do at Changi, I recently change some flights from a 4hr layover to a 12hr layover to rest and explore - hopefully the pool renovations at T1 are finished.

Its easy to get to/from different terminals.