My DD (now 8) who was "spirited" as they call it as a toddler, was actually much better behaved at WDW than she was at home. We really did not have many tantrums at WDW at all. Home was an entirely different story. Maybe you will get lucky. My advice is to follow their cues- you won't know how they are going to be at WDW until you are actually there- they can surprise you. Turns out my DD is a commando like us. She doesn't like breaks and even at age 2 and 3- we could do open to almost close every day for a week with just stroller naps for breaks. She wouldn't stand for a non-park day and would be standing with her stroller at the resort room door telling DH and I to hurry up once she was fully awake in the morning. She has always been a high energy kid.
DD's biggest tantrum while there her 2 year old trip was the 1st day when we attempted the afternoon break that I was convinced by these boards that we needed. We dragged a kicking and screaming 2 year old out of MK, who then refused to nap for between 2 and 3 hours at the resort because she was furious with us. She was not going to sleep at the resort no matter what we did. When we gave up and went back to MK, we had a happy child who immediately got in her stroller and took a nap. We quickly determined that afternoon breaks didn't work with her, and that stroller naps during the day worked great. When you get there, you have to figure out what works for your kid. All kids are different, and advice that may be great for someone else, might not work for you. Just keep an eye out for when your DS is getting tired, hungry, etc. and adjust. If you are doing stroller naps, it may be that you need to find a quiet or non busy spot to get them to go to sleep, or it might take just walking (for DD we had to walk with the stroller and she would fall asleep- I can remember walking in circles once). It may be time for a resort break. If you are doing a resort break, but are not ready for it yet and your son is extremely tired and not falling asleep in the stroller, it may be time to go to the Carousel of Progress at MK, or a movie in WS at EPCOT basically somewhere dark where you sit and where he might take a catnap (DD slept entirely through Country Bears at that age). He might need a snack- burning all that energy running around WDW can make a kid hungry! If he is a picky eater, you might bring the snacks he likes into the park with you. You just find ways to adjust that fit with your child.
Also be flexible not just in those things, but in your activity plan for the day. Just because you have in your head that your child will love certain things does not mean that they will- let them stop and smell the roses and enjoy they things that truly interest them. At 2, my DD didn't care at all about seeing the Castle for the first time and she absolutely did not want to ride Dumbo, both of which surprised me. She became obsessed with any and all characters, Small World, the Peter Pan ride, and the boat ride in Mexico at EPCOT. If your DS wants to ride the boat ride inside EPCOT in Mexico a few times in a row and there is no line, let him.
As far as when a tantrum does happen, first don't stress out. All the parents there can relate to what you are going through. It probably isn't the first tantrum anyone has seen that day. The CMs see them all the time. For people without kids, if they are at WDW a highly kid populated place, then it shouldn't surprise them or upset them to see a tantrum here or there- I know it didn't bother us. If at all possible remove the child from the area/situation until they calm down. Try not to yell or become overly frustrated with your child as hard as that is, because that will just escalate the tantrum. We would find a bench and just park it there until the tantrum subsided. I would just tell DD "I understand you wanted ________ and you are upset, but you can't have/do _________. We are going to stay here until you quit being upset about it". Then I would try to talk as little as possible until she quit throwing a fit. Pretty soon she would realize that if she wanted to do fun things she needed to knock it off. I would ask "Are you done and ready to go do something fun?" and I would get a "yes" and sometimes an "I'm sorry".
Do try to be somewhat considerate to other guests when possible. Our last DL trip, I wanted to reach out and smack the father at the table next to us at our Princess meal. He had a baby who was probably a year to a year and a half old. The baby was crying and screaming because she wanted his cell phone. Not only did he not remove the screaming child from the restaurant or take her out into the lobby area until she calmed down, he proceeded to try to turn it into a "teaching moment" by taunting the child. He would hang the phone in front of the child and tell her she could not have it until she quit screaming for 2 minutes. This made the kid's screaming louder every time he did it. Had he just put the phone away, she probably would have calmed down. As it was, he kept hanging it in front of her over and over telling her if she stopped crying for 2 minutes she could have it, and she kept getting more and more upset as she grabbed for it and he pulled it away and she was absolutely screaming and wailing. The kid clearly had no clue what he was trying to get her to do- all she knew was that he kept hanging the thing she wanted right in front of her, but wouldn't give it to her. This went on for over 20 minutes. His wife and other child just ignored the two of them. I'm not one that normally gets annoyed when someone's child cries at a restaurant because I know that it happens with little ones, but this time it was absolutely ridiculous. It took some willpower for me not to say something to him.
Sometimes, there just isn't much you can do. The worst tantrums DD had at WDW at age 2 and 3 all involved leaving MK and us basically dragging her out of the park with her throwing a fit. We had that happen 3 times. Once was the first day when we tried the doomed break. Another time was at 11:30 p.m. at
MVMCP when we had ridden Barnstormer 14 times in a row without getting off as there was no line (I couldn't take it anymore and gave up after 11 times). DH couldn't take another time, and it was definitely time to go to bed- she didn't want to give up Barnstormer and go to bed- she wanted to keep riding. The last, and absolute worst was her 3 year old trip when she realized we were leaving to go back to the resort and get on Magical Express and go home. Those were all at times we really couldn't just stop and let it subside- even if we would have stopped at a bench, the minute we got up to leave the park again, she would have started up. The worst was the Magical Express time, the tantrum didn't start until the moment we stepped on the boat to go back to Wilderness Lodge and she realized we were leaving Disneyworld and going home, and it continued until we got to Wilderness Lodge. She screamed the entire boat trip. I was so embarrassed and trying to apologize to everyone else on the boat. When we got off the boat, I had more than one other guest tell me not to stress out that it was no big deal and they had been there. When I explained it was because we were leaving WDW entirely one lady said that makes her cry too!
