All this bad talk about the tomini just isn't fair! LOL
I have a tomini and he is awesome. The brown on him is a shiny like color and not drab at all. And the yellow on his fins just brings out the colors on him even more. So don't automatically discount the tomini.
As far as tangs in a 90g I think you would be "ok" just would be careful on what else you add, the 90g can fill upp quite quickly. It's pretty much a 55g but taller and a tad wider. Most of the fish in my 90g don't utilize the top 1/3 of the tank so don't go crazy with your stock.
Just my 2 cents. Good luck with the tank!