If memorable is what you are looking for and money is no object, here's one from my bucket list but is it far from flat. Jade Mountain in St. Lucia.
St. Martin is also very nice if you are looking to balance American/foreign cultures. It's quite developed.
Antigua is less developed but has some very nice resorts and the best beaches in the Caribbean, IMO.
St. Thomas, St. John and the BVI (Tortilla and Virgin Gorda) as discussed are all very well geared to the US tourist.
Aruba may as well be Florida if you can handle the alphabet and currency exchanges. Bonaire and Curaco are less developed versions of the same thing.
More exoctics include St. Lucia, Barbados, St Kitts/Nevis, and St Barths.
Based on your description, I'd avoid Grenada, Jamaica, Dominica, Martinique and any of the lesser known islands. While all have their plusses, they may be a bit too authentic and less developed for your taste. I think people like to bang on Jamaica for no reason, though. I enjoyed it.
I think that's my list. If you wish to rent vs staying in a resort that might change it up a bit. But, if I had to plan a getaway right now my top three would be St. John, Tortola, St. Maartan/St Martin.