A lot of the "good" reefs have been decimated due to dropping pH levels and rising ocean temperatures due to increases in CO2 and changes in biodiversity within reefs outside Marine Protected Areas due to overfishing/collecting of food fish. Take the Caribbean for example. The urchin population crashed. Without the herbivorous urchins to munch away at it, algae took over a lot of reefs. This eventually choked out a lot of corals, which decimated the ecosystems that depended on coral growth. Fast forward to now, and I understand that the Caribbean, while still pretty, doesn't have nearly the same reef infrastructure as it did in the 20th century.
Like Oscar47f said, pick a place and go with it. The freshwater side of the hobby has a thing called "biotopes" where aquarists will set up aquascapes based entirely off of a certain region/area (ex. Rio Essequibo) and only including species (fish, plants, etc.) from there and try to emulate it as much as possible.
For example, if I wanted to emulate Hana'uma Bay in Hawaii, I'd drop the water temperature to like 76 F (or something like that, I just remember being really, really cold), and in a large tank, have a large number of convict tangs, and maybe one pink Pocillopora coral amongst multiple "bommies" of live rock with aragonite sand on the bottom. If I wanted to copy the Captain Cook Monument, I'd want a large number of yellow tangs, with a few overhangs, some triggerfish, a pair of milletseed butterflyfish, and maybe a red soldierfish, along with a pair or two of brain coral and some live rock and maybe a thin layer of sand.
