Trying to figure out a plan for my upcoming Changi situation and would like to get some suggestions as to what is best.

I will be in Singapore for 3 days at which time I have to fly to Bangkok to begin the SQ journey home. Its $1686 for a J ticket BKK to LAX but $4400 from SIN.

I used some UA miles to grab a SQ flight mid day to BKK, will have 3 hours to check lounges out at BKK and then return to SQ arriving 8pm. Then 13 hours later the journey home begins with a flight to NRT and then onward to LAX.

I'd like to spend a little time at Jewel and a decent amount of time checking out all the different things the terminals have to offer since it seems like a really awesome airport.

I first am trying to decide do I keep my room in the city for that last night or better to move over near the airport? I think better to get closer to the airport but is it better to be airside at a transit hotel or landside at the Crown Plaza? I can enter Singapore when I arrive from BKK I assume so I could go back to the city or to the CP. However, when is the best time to explore the airport- at 8pm when arriving back from BKK or early morning before the 9am to NRT? I dont think I am there at the best times to check out all the diff.things as I assume most are closed at night? I guess I can show up a few hours early for the BKK flight and check things out then.

Also if the Changi pool open all hours or no? Is there a fitness center you can access?

I'm usually pretty good planning & strategizing this stuff but I dont know anything about Changi & I've heard you cant really come and go airside/landside like if I stayed at CP can I come in for dinner at the SQ lounge then go back out to the CP?

Any suggestions on how to best plan this last part of my trip w/ this weird routing to go to BKK and come right back are appreciated.