Ok this would be my sugesstion:
2 Severums
2 Festivum
4 Angels
2 Geo's
Raphaels
That would be a peaceful comunity option. for a more agressive comunity u could do:
1 Oscar
2 Green Terror
2 firemouth
2 Acara
raphaels
This is also the division of the species you chose by agressive and peaceful, I wouldn't mix any of the first group with any of the second group if you wanna be safe.
I would mostly agree with this post too. I like both arrangements and it still give you what you want. I have seen plenty of tanks with Severums mixed with Oscars, Green Terrors, jack dempseys, and the like. I think you could more than likely put the sevs in with the more aggressive mix and they should hold their own. I think the first peaceful arrangement alexaniam posted would/should be fine, but the second one may be a bit too much fish for a 90 gallon long term. A male Green terror can still hit 12". I would maybe change that listing to
1 Oscar
1 Green Terror
2-4 Firemouth
2 Raphael Cat
or
1 Oscar or 1 Green Terror
2-4 Firemouth
2 Raph's
This 2nd option would give you 1 bigger centerpiece fish with a few others to hang with. Let us know what you end up with.