-Royal grammas like shade, so kind of hide in dark places. Can be a little territorial, but not too bad.
-Midas blenny...great fish/personality. One of my favorite additions.
-cardinals-pretty big school. When they get 3+ they become a little more agressive. You'd want to add all of the cardinals at one time so there's no fighting for new comers and that would create a large bioload. It's possible though.
-From a few people including myself, chromis have dwindled down to one. Sometimes they just disappear. I personally would rather have other fish than a school of chromis. 2 schools is a lot for a 90 anyway.
-pair o' clownfish
-Sleeper gold head gobies: You'll have a clean sand bed, that's for sure
-Cool wrasse. They've got a rep for having some bad behavior. Can pick on small fish/shrimp, but shouldn't be too much of a nuisance especially since it's a FOWLR
. Another wrasse would be awesome imo
. You have so many options since you don't have coral.
You should be able to buy some chaeto from your LFS
. Just ask them if they have any for sale.
All in all, those are nice choices, but I think with the schools, the bioload would get crazy. Ergo you are sane.