On my Denon AVC 3700 there are two speaker presets, and I think it's possible to have two different speaker setups saved.Not sure of your room dimensions but, if you have room for a 2nd row of seating, you could sit in the front row for quad & 5.1 listening, and back row for 7.1 and beyond.
In my opinion, if you don't have the depth for a 2nd row of seating, then there's probably not a need to expand from 5.1 to 7.1 at the user level (although I do understand the temptation of continued tinkering & upgrading!).
For what it's worth, I went from 5.1 to 5.2 to 5.2.4 to 7.2.4 in our last home (13W x 19L), and the biggest bang for my buck was puttingin the height channels. This rear vs side channel thing you mention is a real issue for quad and 5.1, and sticking with 5.2.4 solves that problem. I wish there was a standard setting in AVRs to change this, but I've never heard of such a thing.