Let me start out by saying it depends…. I know I could go with the standard answer Disney wants you to hear, which is that Disney is perfect for all ages, but lets be realistic here.
First of all, is this going to be your only Disney trip? If so, wait until your kids are old enough to actually remember it. A Disney vacation certainly isn’t cheap, so I wouldn’t want to take a very young child.
Also, keep in mind a day (or multiple days) at Disney can be a whirlwind and very exhausting. You want your kiddo to be able to handle a full day of activity and in my opinion you ideally would like for them to be comfortable walking on their own for an extended period of time. Yes you can always rent a stroller, but you cannot bring the stroller in line with you. If you plan on going during one of the peak travel times then you’re most likely going to be standing in line for a significant amount of time and those little legs and can tire out pretty quickly leaving mom and dad stuck carrying their child for hours.
If you are going regardless with a very young child it is worth mentioning that most of the rides will be able to accommodate them. Obviously the more intense rides like Space Mountain, Splash Mountain, etc. will have height restrictions, but majority of the rides at Disney are pretty calm and your extremely young ones won’t be turned away at the entrance.
A couple years ago I brought along my five year old cousin with me to the park. I really felt like she was at the perfect age because she was old enough to walk the park on her own although we did get a stroller later in the day to give her a break (cast members remember that you get strollers for free). She was also still young enough to believe in the Disney magic. She loved meeting the princesses and Minnie Mouse, whereas her older brother who also tagged along and who was eight at the time wasn’t convinced we were really meeting Cinderella.
Now for the other end of the spectrum – teenagers
Are teenagers going to enjoy the park? That really depends. If it i their first time at Disney World then I’m sure they’ll enjoy it, but keep in mind most of the rides at Disney are a bit kiddie. I grew up here in Orlando and was a theme park regular. I remember in high school not wanting to go to Disney at all because at that point I wanted to ride the big roller coasters and scary rides that Disney didn’t have. Throughout my teenage years I had a pass to Universal and Islands of Adventure and spent majority of my weekends there. There is actually a period of time where I didn’t go to Disney for a few years despite living just a couple miles from the main entrance. Fast forward to today and Disney is my absolute favorite of Orlando’s theme parks because it makes me feel like a young kid again.
So if you’re planning a trip with older children I would definitely scale back on Disney and add in a day or two at Universal and Islands of Adventure.