I second the Marriott Frenchmans Reef. If you can, get a room at Morning Star. They're a set of rooms lower than the hotel and directly on the beach. Havana Blue is a great place to dine and drink. However, be sure your per diem or credit card will handle the load. Typical meals for two run $70+ with a couple of drinks. Coconut Joe's on the other end is only slightly less expensive. Breakfast for one runs in the $20 neighborhood.
Every night was something new in the room. The first night was a gift bag with munchies, rum and champaign. Other nights was a light snack, fresh bottled water or Kaluha. Absolutely fantastic service!
Cab or water taxi to town is $5 each way. Cab to the airport, depending on luggage will run $20 for two people.
Shopping is great and duty free. By the way, the rum is pretty darn good to. I recommend Cruzan, any flavor!
By the way, I was just there a week ago, so this is fresh info.
I stayed at Sugar Bay a few years ago and it isn't bad either. The only problem is it's on the other side of the island and if I remember correctly there isn't anything nearby once you leave their property.
If you have any questions, feel free to PM me or ask here.
Marriott Frenchman's Reef.
2000Flyer