I'd planned on growing Delicious and Church, but it looks like Big Zac offers the most potential. There's a market for F2-F8 seed from the biggest of the Big Zac and a few other large varieties.
http://www.gianttomatoseeds.com/index.html
I'd like to try this, maybe with a Church and a Big Zac. Mark, you save any F2 from your big ones?