I can survive through Spaceship Earth... Don't get me wrong, I like the attraction, but I think it could use an extensive rehab to update certain sections, as well as the omni-mover itself. I hadn't gone on SSE until my last trip in probably 2-3 years, and man, when I got out of that car, I was happy... They're just uncomfortable. Update them, inside and out, possibly reworking the ride system itself.
Other than the ride system, I think a lot more could be done with the planetarium. Let's throw in some 21st century technology, insead of just projections. This as well as the 'light tunnels' could use a major revamp. I'd like to see some more advanced Audio Animatronics as well.
I know I'm asking for a lot, but, although I am in favor of 'thrill attractions', I am also in favor for preserving Disney heritage; there needs to be a mix, but that's another thread

... I'd rather see SSE stay a traditional dark ride, as opposed to another film, as was rumored, or a thrill attraction. Just not the right place.