Just adding my $0.02 worth to this discussion...
I think you should review your architecture if by what you hear, your current one is technically close to impossible (at least with off-the-shelf components). It might be possible with SiGe, or HEMT technology, but certainly not to college students.
Could you conceivably stagger the ADC's. Give each one, say, 10ns to do a conversion, and read each one in turn while the others are still converting? Maybe you could divide your 1GHz UWB into ten 100MHz bands, and downconvert each higher band to 0-100MHz. Just a couple of random thoughts.
Jem