I have been there three times. Twice on a cruise, once for 10 days. Also even looked at going to school down there.
If you are a diver go dive The Wall, insane to see a 20,000+ vertical cliff under water. Dive with the stingrays, its been a while, but I think they still let you dive with them, its a shallow dive, but its wayyy better than snorkeling with them. Also if you are able to then dive the harbor wreck. Most people don't get a chance to dive this since cruise boats are stacked in there most of the year.
Go get some turtle soup, I forget, but there is a place right downtown that serves the best, just ask around.
Go to The Wharf (IIRC) and eat dinner and feed the tarpon.
I think we ate at sunset grill (sunset house?), had a good band, one of the few restaurants right on the beach from what I remember.
Also, there is a place on the other side of the island, none of us could remember the name of it, but it was a decent drive from 7 mile beach, it might have been calypso grill. It was good.
Other than that, just sit back and enjoy an ice cold carib. This isn't a spring break type place, its a relaxing vacation, focused around the water. A lot of great diving.
IF you're not a certified diver and you have time to get it done before your trip I highly recommend it.
Get you a bottle of big black dick. I brought some back, its funny sitting on the shelf, also got a tank...instant beach classic.