Five attractions come to mind:
Under New Management - I'd simply return the original show and add the Disneyland preshow. Iago and Zazu could be better used in Animal Kingdom or something.
Journey Into Your Imagination - Same thing. Bad current show out, good original show in...or something very similar to it with Figment AND Dreamfinder.
Pirates of the Caribbean - Redesign the whole attraction to more closely resemble Disneyland's, with perhaps some of the cool Disneyland Paris audio-animatronics.
Test Track - World of Motion returns. If everyone so desperately needs the speed rush at the end, it can even be left in. Just give me the original inside, with updates to the audio-animatronics and spiels where needed. Welcome back Gary Owens!
Wonders of Life - Update the interior to make it more "today." Give Body Wars a state-of-the-art makeover (maybe 3-D as well?), and leave Cranium Command and The Making of Me alone. I might also extend the building so that it comes out to the main walkway and doesn't seem so hidden behind all the trees. I've always felt that was it's greatest liability.
I disagree with all the Fantasyland attraction updates, though. Maybe they could use a fresh coat of paint, but the attractions themselves hold up well, in my opinion, anyway. My only suggestion would be the previously mentioned remodel for the land itself. Disneyland's current Bavarian look is so much more enchanting than the carnival look of The Magic Kingdom. I think some things SHOULD be duplicated between Parks, when they're good enhancements.