We are bringing my 19-month old in a few weeks, and we brought his brother 2 yrs ago when he was 18 months old. This is my take on it...I do think it is possible to have a great time there at any age (we always have!). But, I do think this is a little bit of a difficult age. 18-months is "mobile," but not really so mobile that you can let them get down and roam around in a place like WDW. So, they WANT to walk and run around, but if everyone else is going to get to do the attractions they can't. There are a few exceptions to this. I know that my older son absolutely LOVED Donald's boat in Toontown. Bring extra clothes for that one, and socks (we let him wear his socks, getting them wet, to avoid direct contact with the spongy floor/athlete's foot danger). It is hard for kids at this age, because as we are roaming around exploring WDW, they are often strapped into the stroller or passed between hands while being "switched off" on rides. So, just remember to keep these things in mind. We have decided that on our first day, we will spend time at the hotel pool, walking on the boardwalk, etc. and not go to a park that day. Those things will allow him to run off steam more, and we wount' be counting the minutes until we can get back to the park. I don't want to unstrap him from his car seat after that long drive only to strap him into a stroller. Try to do as many rides that they can do, too. Also, schedule in plenty of roaming time on Tom Sawyer Island and the like. Although, unfortunately, this will be a workout for YOU!!! At this age you have to follow them everywhere, it is not like you can let them wander off in the Bugland playland or other places, even if the exits are blocked. See what I mean? It is just a challenging time. Good luck to you! (I hope I get good luck too, being in the same boat.)