Has anyone ever had problems booking Caribbean vacations (room+flight) through the discount websites

Has anyone ever had problems booking Caribbean vacations (room+flight) through the discount websites such as Expedia, Orbitz, inexpensive london hotels Hotwire, CheapCaribbean, etc? I always travel with Hilton in the U.S. and book through them because of the reward program. I am trying inexpensive london hotels to plan a honeymoon in late August 2011 and don't want anything to go wrong at the last minute.
P.S. If anyone has any strong feelings (positive or negative) about the destinations I have tagged, please share! My fianc wants beautiful beaches and top notch dining while I want snorkeling\diving and historical sites to visit.
I've used Expedia and didn't have any problem. When you enter your information there are sections to input your frequent flyer number and Hilton Honors ID number to receive points/miles. All miles and points showed up on my accounts a little while after my trip. You can also chose your seating on the airplanes.
We've used all the sites for hotel, air and car rental and have never had a problem. I just got done cancelling a flight that I didn't get cancellation insurance for and got hit with a fee from both Orbitz and Delta. I would suggest either getting a refundable ticket, obtaining the coverage or booking air through the airline site itself. We lost half of our air by not getting the coverage, so take note...
Aruba has some really good beaches (although some are very crowded), a huge variety in dining at all price points, but not very good snorkeling/diving. You can easily see the sites in a day tour of the island.
The British Virgin Islands have the best snorkeling/diving of the destinations on your list. Actually, if you want to snorkel right off the beach then your best bet might be St. John in the US Virgin Islands. The beaches off of Caneel Bay as well as the underwater national park at Trunk Bay have excellent snorkeling accessible by simply walking into the water and swimming a few yards. inexpensive london hotels Diving is also available in that whole area around the BVIs and USVIs. There are some beautiful beaches in the Virgin inexpensive london hotels Islands along with good food and a few sites here and there.
I think other really good snorkeling inexpensive london hotels and/or diving destinations inexpensive london hotels with great beaches and food are Grand Cayman and Turks Caicos. Bonaire is also known as a good diving spot but I don't know about the quality of the beaches or food as I have never been there.
A small note of warning inexpensive london hotels is one I'm sure you're already aware of but late August is prime hurricane time. If I were you I would purchase travel insurance that covers hurricanes. Aruba is somewhat out of the hurricane belt although not completely immune, as no place is.