I figure if I want a map, ther are plenty of places to get one at WDW. I do create an itinerary. The itinerary has park hours, our plan, EMH hours, dining ADR's. On a second sheet, I fit the rest of the trip confirmation #'s, flight info (for the group), remaining balances - if any, and maybe directions if there is a restaurant, grocery store, etc. that we plan to visit. On a third sheet, I put a copy of the back of our park tickets, which I store away from our actual tickets.
If we get a car, we do grab the maps that the rental car companies give out, but I've learned not to trust them 100%. Somtimes they distort distances a little.
For flying on SWA, I don't think I've ever needed to give them more than my name at check-in. I always print my receipt whenI buy tickets so sometimes I just bring that, but for WDW I ten dto only bring the conf#, and I've never had a problem. You would need the conf.# to print boarding passes for return flight though.
If you are flying Southwest - or any other airline where you can print your boarding passes ahead of time, you'll probably want to do so.
Otherwise, to be honest, I really rarely need or even use much of it at that. Usually to check in most places want to look you up by last name over your conf. #. You are better off picking up a time schedule at WDW, because sometimes there are changes - and ones you pick up at the resorts/parks are more likely to be accurate that what you'll get off the web. When you check into any WDW resort,they will give you a folder with maps and all. The parks have these great little cards they give out withthe ADR bracelets that list the EMH stuff very well. OTherwise, just grab a time card at the entrance of each park if you're concerned with parade times and the like.
Do remember to bring a valid photo ID with you. Traveling without that is a real hassle!