If you hold some locally issued credit cards (DBS Altitude, Citi Premiermiles, SCB, etc) that give you Priority Pass lounge visits, you can use the SATS lounge at T3 in Changi (this you probably already know, there are other lounges as well, SATS is better) and three restaurants in SFO that are in T3, T2 and International terminal. If you have AMEX Platinum (as locals call - '1712 card') you can go to Centurion Lounge which is in T3. International terminal, T2/T2 are interconnected airside.

Your luggage won't be checked-thru. You will need to pick up your luggage at SFO and re-check at the final destination. When you pick up your luggage after customs, do not exit to the Arrivals section, rather look for the sign that says Connection. Take your luggage and re-check there. You will avoid the misery of doing this at the departure section and going thru security again.

Michigan in November, from Singapore...can hor? I am sure you are going to pack adequately - you are gonna have at least a 30C-40C difference in outdoor temperature.

P.S. Don't expect any kopi, teh, laksa, char kwai tow, nasi lemak - any food you are familiar with in Singapore to be available there. On the other hand, you will have the opportunity to enjoy excellent steak instead of 'western food' at hawker centers and try Chicago-style deep-dash pizza.

And don't wander alone at night. Even not alone - don't, see what happened at NYC this week...

(a former Singapore resident for >>10 years)

Take a look at ticket prices departing from Singapore... it has been >$2000 USD in Economy since Covid (at least for SQ) and there is no indication to come down - too much demand.

You should ask your questions in the Singapore section - you will get qualified answers.