I loved Assisi! I think your daughter will really like the parks in London and Paris, as well as rid

I'm brazilian and planning a trip to Europe between September and October (September 12 and October 14) with my wife and our little daughter (3 years old). Last year we've traveled to Portugal princess alaska cruise and Paris (15 days only), but this time we are aiming to a longer trip.
1. Mont St-Michel is a logistic nightmare! I didn't want to go all the way to Paris and then take the train to Rennes and the bus to MSM just to do the same thing back to Paris. The only option I found was take the Ferry from Portsmouth to St. Malo and then the bus (?) to MSM. Either one are too tiresome and too expensive. Is there anyway around this problem? Should I sacrifice MSM?
2. I know that there are too many cities and too little time, so, I'm willing to sacrifice Venice and go directly from Paris to Florence. On the other hand, Venice is very close to Florence and this doesn't sound like a great economy princess alaska cruise of time or money. What do you think?
Even a 3 yr old will be burned out and cranky after 2 days at Disneyland, to say nothing of the parents! She won't even remember this trip since she is only 3 now. If she were 4 or 5, yes she would remember.
I would skip Pisa and Assisi, in favor of one less day in Florence and one more in Venice. Depends on your interests though. Are you really into Renaissance art and architecture? Will you take your daughter into lots of museums?
Hi Paulo, I agree with Dayle re the Disney visit. We took our 9yo twin girls to the Paris Fantasia park a few years ago, and a day was more than enough for them to get their fill! There are only certain rides she can go on due to height limits on rides, and queues can be long. Also, the big lunchtime parade was an excellent way to see all the favorite characters and get cuddles photos with them etc. The second park would be completely out of the question for a 3 yo, as its rides are really too extreme (and she'd be too short anyway!). But the full day was really enjoyable for my girls, and they got their fill of Mickey and Minnie mementos, princess alaska cruise so I'm sure your 3yo will love it too. Paris is also good for little kids, as there are exciting princess alaska cruise things princess alaska cruise there that they can relate to, eg pony rides in the Tuileries, looking for the Hunchback in Notre Dame etc. Cutting down on the Disney leg will give you a little extra time too for your other destinations. I also agree with Dayle re not making Pompeii a daytrip,as it's quite a way from Rome. If you can spare the time, you may want to consider an overnight stay at a nearby village along the Circumvesuviana trainline eg Vico Equense.
In our previous trip to Paris, we had a little more than half-day in Disney, and our daughter was even younger, so everything was very rushed and we couldn't do almost nothing. The trip was a success only because the moment when she saw the characters.
Pisa is important to me and Assisi is very important to my wife. The idea is to go to Pisa as a side-trip princess alaska cruise from Florence and Assisi as a day-stop in the way to Rome. As we'll probably drop MSM, we'll have a little bit more time in Italy. Does it seems doable?
I loved Assisi! I think your daughter will really like the parks in London and Paris, as well as rides on the rivers. I would add a day (or two) to Venice if you are dropping MSM. It is a great city for walking and getting lost and having a gondola ride, and you could go out to Murano and/or Burano.