My kids are 5 and 8 and enjoyed legoland more, but 10 year old probably will like Disney more.

I’d stay onsite if you can afford it. Especially with young ones so you can rest. We usually take breaks during the day and come back to the park later. If your going for 4 days you wont feel rushed. Wasn’t sure how many days in the park? If stick to one park per day if you’re not familiar with them. It’s easy to get overwhelmed. If you don’t go there a lot, I feel people try to do much and then get disappointed. If not onsite, then a hotel close by because your kids are young. Yes to fast passes!