I just hope they don't change any of the classics...
Like IASW, Winnie the Pooh, TTA, Teacups, Tomorrowland Indy Speedway.
I would change a couple things about Splash Mountain. First of all, the "logs" are always backing up and slowing things down. And secondly, there's a drop that's goes down, back up, and down again mid-ride. I really love the part and I think it'd be cool to add one more drop like that. Also, sometimes the music sounds really...cloudy. Like I can't make out what they're saying.
Ideas for new rides...
Monsters Inc "Door" ride. I think you all know what I'm talking about.
Little Mermaid
101 Dalmations.
Cars
Stitch's Great Escape is just...pointless. A lot of people will agree with me.
Kali River Rapids, it'd be good if there was actually some place to put your stuff where it WON'T get wet. I know there's that big tub in the middle but it always has like an inch of water in it. I love the ride but I just don't like my camera and stuff getting wet.
Tower of Terror, I wish it were longer. More drops, etc. =)
I'd also like to add I don't know why a lot of people don't like the Figment ride. I thought it was really cute and a great way to get out of the heat.