The age of the tires comes to mind along with when it was serviced, fuel filters, air cleaner last change, air drier cartridge age, if it has an Aqua-Hot it needs attention annually. A leaking jack could result in an expensive service in the future. Check for rotted stitching/material on the patio and slide toppers. When was the generator serviced, any issues. Condition of the side wall fiberglass as crazing is an issue with some model years, mine included. Has the serpentine belt been replaced and the A/C drive belt? I'm sure you will get additional suggestions.