OP, first of all, if your child's behavior is disrupting the family so often, it's time to have him evaluated. You are not a bad mother, so don't listen to these posters saying that it's a discipline issue. It's likely not, especially if you have an OLDER son who you've been able to successfully discipline.
We have that same dynamic in our house. My younger son, now 4, has EXTREME tantrums, rages, meltdowns, etc. This has been going on with a host of other "issues" since he was around 1 year old. He is in the process of being diagnosed/evaluated by a child psychiatrist. He has been receiving services since he was 14 months old and is now in special ed. preschool. I say all this because, to the outsider, my son seems like a complete angel. That is, until he loses control over something so minor most people wouldn't even notice it. Then, it becomes "that child is out of control and it's probably the mother's fault for not setting him straight". Trust me, you don't want to have to deal with that sort of judgment.
Anyway, the point of my post is that we were considering doing just what you are thinking of. However, our son was SO bad that we couldn't even bear to leave him with relatives. So, we decided to wait. We went this past spring right after he turned 4. He did SURPRISINGLY well, although, to be fair, he's been going to
Disneyland almost weekly since he was born, so it wasn't a completely new experience for him. The plane trip (cross country) was, though, and that was my biggest fear, and he did really good. Our older son has Autism, and both boys were in great moods all week at WDW and it was actually our OLDER son that did the melting down (and only on one day, so we did good!).
I would think about waiting a couple years, if necessary. You will feel horrible all week because your other son is not there (bad behavior aside, you know you love the little monster)

I did recently completely cancel a long weekend I had planned at the Disneyland hotel over my birthday for me and the boys, because my younger one was going through a rough time. I didn't think it would be a very nice "vacation" if I was constantly disciplining my son or having to listen to him scream and meltdown over everything that was out of his control. So, I just cancelled it. Life goes on; we will try again in the future.
Have your son evaluated (it's free through your state's early intervention program) just to make sure that his behavior is "typical age appropriate" behavior, and if it's not, you can get educated on some treatments and techniques that will help you ALL have a happier family life.
Oh, and the number of times one of my children has "ruined" something for his sibling...probably well over 100. I know exactly what you're talking about here.