IPad is the magic bullet for us!

We bought our then-4-year-old her own pink rolly-bag carry-on last year for a plane trip out West. Was helpful for the airport and she looked so cute pulling it through the hotel lobby.
Portable DVD player was helpful on the plane.

Just wondering if people have a "must have" for travel (plane or train) for their 5 year olds (or thereabout). Anything that made your trip (and theirs) much easier? We have both a long flight and a long train ride ahead of this summer. Thanks!