You might want to check out this thread I did a while back.

In my 4x12, I've got 2 Eminence Governor's and 2 Eminence Wizards in an X patter, and they are great! It's a very versatile combination. The Governor's are similar to Celestion Vintage 30's and the Wizards are similar to Celestion G12H's. I play a little bit of everything, and they seem to cover it all very well.