those are really nice tanks...
I hope you went and checked out King Eds in New West as they have an insane amount of tanks on hand and they love to wheel and deal for cash.
Your question is completely dependent on what you (your wife
) would like to keep in your wave tank....
any ideas on what kind of fish/coral you're going to want?
If by mixed, you mean sps, lps and softies then you could most definitely could go with a t5 fixture, I would recommend at least a 6 bulb fixture for a tank of that depth and length.