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In Raja4 Divers house reef, there is a 4-foot giant clam (~ 50 years old as giant clam growth rate is about an inch / year) in 20-foot depth with soft coral growth on its shell. You can see Walking Sharks roaming around in the evening. Very pristine reef.
You already mentioned Key Largo, which offers shallow reef diving over a flat bottom (but also deep wreck options for those who want them). Bonaire shore diving would let you cruise the upper strip of a sloping wall, and there's a site called The Cliff that'd be really nice for this type of dive.
One I haven't seen mentioned is St. Thomas in the U.S. Virgin Islands. I've only got 4 dives there. 2 Were referral OW training dives (max. depths 25 and 35 feet deep; no idea whether they were named sites or not); 2 were recreational dives on a cruise stop, at Armando's Paradise (max. depth 43 feet) and Navy Barges (max. depth 39 feet).
I think roughly 40 feet max. is more practical than 30 if not shore diving, but diving over a flat 'hard bottom' may be more mentally reassuring than over a sloping or vertical wall.