My husband and I are in the "you packed it, you carry/roll/lift it yourself" group. So yes, my vote would be for 2 smaller bags assuming that you each would handle your own.
We always carry on unless required to check our bags for some reason. We keep our carry-ons to a maximum of 20 pounds. Those are our "big" bags.
I use a 22" (including the wheels and handle) Lipault spinner. My husband uses an RS convertible backpack. My "personal item" is a tote. His is a CPAP bag. We use this combination on both foreign and domestic trips.
Our European trips are typically 4+ weeks. We pack for a week and a day, and do laundry weekly. So far that's worked for 5 trips to Europe totalling about 26 weeks.
He's 67 and I'm 69. If we can't manage those bags in all the situations needed on our trips, we need to get smaller "big" bags and take less, or step up our twice weekly weight training.
There are many times when I travel by myself, without any BOB (beast of burden). I believe that if I can't handle my two pieces of luggage on my own, I shouldn't be going. Knock wood, so far I'm still able to do the most challenging luggage maneuver -- putting the 20 pound bag in a bin over the seats -- regardless of the mode of transportation.