I usually bring a medium sized totebag and dufflebag in the checked luggage. Both are small enough to take on as carry-on if we have breakables.
I don't need as much stuff in my carry-on for the return trip, because I don't need all my toiletries and park bag stuff in carry on for the ride home- even if my luggage was lost, I have full size everything at home anyway, so other than meds and my electric toothbrush, which I'd be upset to lose, those things move back to the checked suitcase. I also carry a pretty small purse, which comes in handy.
I pack light and do weird stuff like bring my beat up sneakers and flipflops from the summer for my winter trips- I pitch them out before I leave, and I have more suitcase room. I know this doesn't work for everyone, but generally, the way I run around, my summer sneakers have one good park trip left in them and after that, they're ready for the trash can anyway. Some people do this with their old socks and undies too, but I'd just feel weird about throwing out my underwear each day. :lol: If I had to pack really light, I'd do it though.
If we buy too much stuff, my purse fits inside the small tote with the smaller souvies, which is then my "small personal item" that can fit under the seat, there's extra room in my carry on bag for more stuff, and in a dire, "we bought too much junk" emergency, DH can carry the extra small duffle as his carry on since he generally doesn't use a carry on bag anyway.
The tote bag also doubles as a beach bag for pool or waterparks.
I learned my lesson after too many vacations where I had to find a Target or
WalMart to buy a duffle bag to get stuff back home!