leoskee, I don't mean to ruin your thread or anything, but look into these larger tanks these guys are making available to you.
Reason 1: foot print of the 90 will leave something to be desired. I'm not saying there aren't great 90 gal set ups out there, but you will appreciate the wider set up of the 120 (or more).
Reason 2: we have no discipline. You'll look at it and say, "damn, I could have gone bigger". If I had bought a 120 instead of a 90, I can tell you that I probably would not have upgraded to a 180 (30 gallon upgrade? That's crazy... double up for me). Go ugly early to avoid the rush.