If I was to come to St. Croix on vacation, or I was recommending some things to a good friend, this is what I would tell them:
1) rent a car - even if you are staying close to the dive shop, there are so many more things to do on the island that require transportation
2) stay somewhere off the beaten path - there are many villas, vacation houses and condos for rent, many for cheap
3) stay on the North shore - with the best views, and close to the best diving, this is the place to be
4) shore dive the Frederiksted pier and Cane Bay as much as you can possibly stand to be in the water
5) do some boat dives with Cane Bay Dive Shop - seriously, we have one thing over every other shop - location location location... Our longest boat ride is 15-20 minutes, which is to Salt River, most of our others are 5 minutes or less...
There are three basic areas for diving around STX. West End - a few nice reef dives, a grouping of 5 shipwrecks, and the fabulous Frederiksted Pier. North Shore - Amazing wall that drops to over 3000 feet deep within a half mile of shore - this area runs from Hams Bluff to the point just East of Cane Bay, and the deep stuff is a little farther away from shore farther East, as far as Salt River. There are some dive sites in front of Christiansted, but I have not been impressed by them at all. Lots of sand, dead coral, and just no color. SCUBA (captain Ed) actually calls the Cane Bay mooring "The Ultimate Wall" but we hardly ever see them out there because the boat ride is so long from their shop in Christiansted...
Dive Experience is obviously one of our competitors and I don't know much about them other than their boat is relatively small. We have two smaller boats (4-6 passengers max), and a 36' Newton, we definitely have the best boat fleet on the island...