Why does the glass have to be 3/4" thick? Why not 1/4 or 3/8" then you could have it sit in a rabbeted ledge plus maybe one or two cross supports between the long rails. I've set 1/2" corian in a mitered frame that way and it's plenty sturdy but having the glass be the same thickness as the top complicates things plus probably jacks the cost up even higher.
I agree. I just made my first call to a glass company for prices. 3/4" at the dimensions I would need would be $171.00. They asked what the application was, and it was their opinion that for my uses it would be more than sufficient to use 3/8", the price would be $33.00, and as long as I didn't sit on it or "put all my pots & pans" on it it would be fine.

I would keep the overhang...better symettry and it accounts for the base moulding.
Okay, so if I have an overhang how do I attach the mirror? I think the mirror should line up with the rails, not flush with the edge of the overhang. This puts a 1x frame on it's edge in the middle of the table. I can't picture how I could attach it.