What I do is head to the Lionel and MTH booths for catalogs (you have to pay a one-time $5 catalog list fee, which also means they will mail them to you if you don't pick them up at York, for MTH or be a member of the MTHRR Club to get their catalogs). Both companies give you the catalogs in large, heavy-duty plastic bags which can hold quite a lot of additional stuff. When they are full, I head back to my vehicle to drop them off.
The trip back to the vehicle also serves a double purpose for me as I bring a cooler full of my favorite non-alcoholic beverages (I try to avoid drinks sweetened with anything artificial and anything sweetened with corn syrup), and the trip back allows me to get some refreshment and stay hydrated. I also sometimes bring snacks, but the food on the fairgrounds is good enough most of the time.
Andy
