I like your way of thinking! I'll give you a list of some cool animals you could get.
-A group of Huchtii, Ignitus or Carberyii anthias would look amazing in that tank. All three of those species are unique and not often seen in the aquarium trade, but are hardy enough for people with lower experience. They will shoal at higher densities, but for that size tank I would go with 3-5 maximum. Never start with an even number.
-A very cool addition to the tank could be an Echidna eel of some species, such as the snowflake, chainlink or Skeletor (my favorite). Snowflake males have sharper teeth than others and may pose a risk to some fish at larger sizes.
-A miniature puffer from the genus Canthigaster could be a very cool addition to the tank, but you would have to be careful with corals as they may nip certain fleshier ones. If you want to be really sure about coral safety, get a Leopard puffer, they are not found in coral-rich habitats and therefore don't eat coral.
-Any of the dwarf angelfish of the Centropyge genus would be really cool to have, avoid flame, flameback, and coral beauty because they are all very common. I would recommend a Potters angelfish for a unique look and lower coral risk.
On to corals/inverts!
-A coral that I don't see a lot of in many tanks are Cynarina, or button corals. They come in a wide array of colors (I can link you to some sources for high end rainbows) and are very robust. The problem is, they don't grow new heads so you won't make a return from the investment.
-I don't often see Acanthophyllia often either, similar to Cynarina but often with more desirable shape and/or color. They are a bit more commonly kept in the hobby, I have three.
-If you would want to go with an anemone at some point, you can never go wrong with a Macrodactyla doreensis, or Long Tentacle Anemone. They willingly host many species of clownfish and are big, bold and beautiful.
-Some cool inverts are the Halloween and electric blue hermit crabs, just like the normal hermits but less often seen in the hobby and very flashy.
-If you don't have any clean up crew yet, you could scour Live Aquaria for a special type of Turbo snail that is yellow instead of brown. Super cool and they are sold in packages on the Diver's Den nearly every day.
If you go the route of the anemone (no matter the species) you could try one or two of the Anemone shrimp species, like the Pedersen's shrimp. Just know that if you choose to get an eel or any basslets (like the Candy bass you mentioned) they may be turned into an expensive snack.
You could try a Strawberry crab, a large omnivorous scavenger that will handle the same amount of work that you would need two or even three emeralds to take care of. Just remember to keep them fed lest they get hungry enough to try and eat your fish.
Another super cool addition could be a slipper lobster, most often sold in food markets but occasionally available to the hobbyist. Just keep in mind that they will try to eat clams. The species sold as food get massive, so I would advise you to try and find one of the smaller species (I may be able to help you locate one).
-If you plan to keep only large, active fish you could try a reef lobster (Daums of Hawaiian are the smallest I believe) but they may still pose a risk to sleeping fish so I wouldn't advise one.
-If you really want a challenge, you could try some Sea Cucumbers in your tank. You could either go with the basic Tigertail or you could try something like a giant cuke or black Holothuria.
-And finally, if you really, really want to try something completely outlandish and crazy you could try to keep pygmy squid, but there is little to no information out there on their care so I wouldn't advise this.
Good luck with the tank! I'll be watching to see how it turns out.
