I agree. I have not had a valet check on anything larger than a 717(?). Even I think some CRJ9 I think I've kept my roller bag.
My carry on bag I can put ~7 days worth of clothes. Whether that's 7 days for one person or 3 days for one person and 4 days for a second, the 7 days has been pretty solid. My backpack hold all my electronics... laptop, tablet, headphones, chargers for everything and some pens. I have put one day of clothes in the backpack, but not much more than that. Those are my two items.
Again, difference between "gate checked" and "valet checked". It all depends on the tag (and what they're trying to accomplish). If it's a white, "sticky" tag, you're picking it up at baggage claim. If it's a small pink/red tag that's attached with string, it should be returned at the next jetway.