For the media tour I'm only interested in class changes pretty much, but yeah they're super limited on content they don't actually play the story or anything, just a random dungeon without context and then can run around a zone with some dummies so they can test rotations. While I don't care much for the guy, Mr Happy coverage of the media tour is usually very complete showing every class being played in their own videos while he explains the changes and show screenshots of the abilities so it's great to see all you need to know. Also you get to see the new classes properly and all their skills, at that point people will also start theorycrafting the basic rotations and you can setup macros to do your bars automatically which I like.
As for the length of the expansion I don't really expect much change but honestly don't know how long all the expansions are to begin with. There's clearly going to be several arcs(discovery/exploration, hunt for the big snake bird, tournament stuff against the other team, then likely gold city shit and the big bad stuff mixed in) but they can easily fill that up with stuff to do so I'm not worried it'll be too short personally.
Also very sad news indeed, the character creation rework is delayed...by 3days. I like that they bother explaining why it's a whole three days late like people are going to be crazy about it. Also lots of changes compared to benchmark version which for the most part seems to make the chars look better.
A Final Follow-up Regarding the Dawntrail Official Benchmark | FINAL FANTASY XIV, The Lodestone