This is exactly why I bought a Mega Cab and put the long bed on it. I have 4 friends with the QC and one trip sitting in the back is one too many when you're 6'3". For less than $33k, I got the truck I really wanted.
My son is 6' 3" and he doesn't have a problem with his 04. 5 QC and he has two young boys in car seats. On long trips they often take his mother-in-law, who sits in the front and his wife, who is tall at 5'10", sits in the back with the boys.
My son and I both feel that if Dodge made a mega cab with a 8' bed, we'd still get the quad cab. Nothing a thing wrong with it.