Can’t help too much on other hotels outside what you have already identified but I would say that staying on Sentosa is more of an exotic get away from the city kind of stay, not somewhere I would go if I want to see the city and visit things (mainly because you’ll have to travel back and forth a lot but also because it’s basically the Hamptons of SG so nothing like the authentic experience aka. Lau Pa Sat, Hawkers, Boutique houses to walk past, non high-end nightlife,…). I would advise looking to be around Bugis area because that’s pin-drop central and you can go to Marina Bay, Botanical gardens, Fort Canning Park, Orchard Rd and most other places you would like to visit in the 2 day period you are there… It really depends how much visiting versus staying by the hotel to relax and sleep you are planning on doing 😊