Map's, many, many maps.
I usually take 2 of each park, DTD and all the leaflets, one to read and one for posterity.
I have done this for the last 2-3 trips I've been on and plan to again in 3 weeks time!
I'd argue that AK needs more love right now, however I will consent that DHS appears to have lost its path a little and needs to have a look at how to return to its original theme of the golden age of movies.
Indy Speedway needs a complete tear down and rebuild:
They should theme it after cars and use alternative fuels.
Jungle Cruise definitely needs some love too, some of the AA's need a good coat of paint, although I'm not sure it needs a full refurb yet.
UoE is completely outdated, there...