There are lots of rides that your daughter can go on at almost-3! As
@wampuscat7 pointed out, you can search the Disney World website to get an exact list of what does/does not have a height restriction. If there are other rides you want to go on that aren't quite as child-friendly, there's always the child swap option, where you ride while someone else in the family watches your little one... and then that adult gets a turn riding once you've returned. In general, there is SO MUCH to do, for everyone, of all ages.
How long would you be looking to go for? What are you most interested in seeing/doing while you're there? Is your family likely to want to watch the shows in the parks? Look for thrills and chills on the bigger coasters? Staying onsite or off? Will you go for a deluxe hotel or stick to a value on tight budget? With an October trip, will you want to splurge on Mickey's Not-So-Scary Halloween party tickets? Or munch your way around EPCOT's World Showcase at the Food & Wine festival? Character dining? Meet all the princesses? Or the Fab 5? Or Winnie the Pooh? There are so many decisions to make - no rush to make them, just look around and get an idea of what appeals to you most - and what fits in your budget. Some will probably depend on your daughter - little girls around 3 are in prime princess age, generally speaking, but some kids never hit the princess phase... But some should depend on you, as well - if there's something you really want to experience, prioritize that. It's your vacation, too!
People here are pretty helpful - though you'll get a TON of conflicting opinions for just about any question you ask.
But look around, ask your questions, and have fun planning your eventual trip.
I took my son at 2 1/2 and again at 3 1/2 and they were both magical trips... there's such a huge capacity for wonder in kids that little, and Disney World is the perfect place to engage their sense of wonder and magic. Have fun!
