Hi Jeff,
I've been to Bermuda more than 20 times, and I've really enjoyed the diving there. While it is not as lush as the Caribbean, in terms of either fish life or reef life, there are a great many shallow wrecks, in various conditions, to be explored.
I'm not sure which resorts you have contacted, but the dive op that I am most familiar, and happy with is "Dive Bermuda". (
www.bermudascuba.com) They have shops located in Hamilton, at the Hamilton Princess Hotel, and at the Fairmont Southampton. The dive shop at the Fairmont Southampton, is located on the south shore beach of the Hotel, which is approximately 100 yds. away from Horseshoe Bay. It is "the next beach". (I'm not sure if "Horseshoe Bay" is the same as "Horseshoe Cove"). Most of the boat rides from their shop, to a variety of dive sites, are less than 15 minutes in length.
While I've never stayed at Elbow Beach, I have heard good things about that resort. I don't know if they have a dive operation at that location.
In terms of things to be aware of, in addition to the usual "bring your own gear and suit,(lightweight) if possible", keep in mind that there were no rental cars in Bermuda, which leaves your options for transportation: taxi (somewhat expensive), bus (less expensive, but travel is on their schedule) or a rental scooter (not a big help if you have dive gear!). That might be something to factor into your thinking as you decide which Hotel/dive op to book with.
Enjoy your trip,
Mike