Sure, gimme a day to look up the hotels closest to the spots.
For seeing marine life your best bet is to get lucky. No seriously. I spend countless hours scouring my spots and I have been able to drawn some very loose conclusions but its still a crapshoot whether or not the critters feel like hanging out on a given day. Patchy distribution if you will.
The seagrass beds will be the most consistent just because they provide constant shelter and harbor a wide array of critters. You can find some sea whips and smaller gorgonians in the sandy flats around grass beds but the really big and cool ones are all offshore. Only problem with that is many of the seagrass beds require a boat to access, there are some that can be reached by wading or a short swim.
Structure and the seagrass beds are very very site specific. Fixed stuff like wrecks, rocks, and debris (old docks, seawalls etc.) don't move but you have to know where they are, and be able to get to them. The seagrasses are a little more cosmopolitan but would still require an easy access launching area. I will dig through my field notes and try to line something up for you that should be easy to find.
The reasons to avoid getting in the water with the rocks at CB:
1. Currents=> Very strong and prone to sudden changes. That stretch of CB is notorious for drownings........I think 7 in the last 5-10 years.
2. Visibility=> Slim and none due to #3.
3. Wave Action=> Being releif on an otherwise smooth(ish) bottom they cause errant and erratic waves to crash in and around the rocks constantly. This stirs up sediment and kills the visibility. Plus the waves are prone to bash an unwary individual on the rocks.
4. People=> The area is frequented by vacationers and anglers so there is a ton of not so nice debris out there to get jabbed with or hung on. For some reason visitors to NC fishermen or not, seem to think a snorkel in the water is a target. I have been hit with bottom rigs, gotcha plugs, some moron hit me with a bass plug, and rocks or shells hurled by unattended (not always) children.
Hope that helps.