Expansion and Rehab/Referb are two different things here. I think DAK needs an expansion, but the rest of the park is overall, just fine, while DHS on the other hand needs to re-imagine entire sections of the park and update/change out existing attractions, but an entire park expansion may not be entirely needed as bad.
If you look at each park and how many actual RIDES each it each has...
DAK - 7 - Dinosaur, Primeval Whirl, Tri-Spin, Everest, Kali, Safari, & the Wildlife Express Train.
DHS - 6 - GMR, Tower, Coaster, Toy Story, Star Tours, & Backlot Tour.
The last of both lists I barely even consider rides. The rest of the parks are shows and other entertainment, which if fine and fun, but when you compare to the other two parks...
MK - 19 - Railroad, Buzz, Astro, TTA, Space, Speedway, Teacups, Dumbo, Barnstormer, Pooh, Pan, Small World, Mansion, Riverboat, Thunder, Splash, Pirates, Magic Carpets & Jungle Cruise.
Epcot - 10 - Spaceship Earth, Nemo, Soarin', Living with the Land, Imagination, Test Track, Mission: Space, Ellen's, Sum of All Thrills, & Maelstrom.
...both DAK and DHS could use a little help to balance things out.
Now I understand that Disney is more than just rides. In fact, as a CM I hate that there are some tourists that automatically turn their nose up to a "show" because they want "rides", but there needs to be more to do at DAK and DHS, especially after 5:00pm when most shows finish for the day.
For an expansion, I'd love to see South America added to DAK with a coulple of new rides, maybe one with an "Up" tie-in if they must, some awesome new animal exhibits, and lots of great food & cultural entertainment.
For a refurb/redo/rehab, I'd love DHS to replace Voyage of the Little Mermaid with a Princess & the Frog show, enclose Theater of the Stars for the rumored Tangled show, upgrade Fantasmic, change Pizza Planet to a Muppet's themed eatery, change Backlot Express to Star Wars cantina, move/upgrade Jedi Training to Sounds Dangerous theater, change Honey, I Shrunk the Kids Playground to Bug's Life playground, and give GMR a huge refurb with 1 or 2 scenes replaced or changed drastically. All of that is just using what you already have to bring in new things to update the park and bring some cohesion to the park. That doesn't include drastically expanding Pixar Place or demolishing LMA/Backlot Tour, etc.
Honestly, if that's all they could give us, I'm fine with that for a while.