I did not expect my child to have free rein. As I explained, we did bring Wii games to keep him occupied (knowing they had a Wii system) and they did not want to set it up for him. There is only so much that you can pack in the car so we were limited as to what we could bring.
Did you actually check with them before you left home to be sure your child would be allowed to use their Wii? If so, and then they didn't let him, that was quite rude of them. If they didn't tell you that the Wii would be available, then I'm afraid you shouldn't have assumed it would be. Even though we have a Wii, and our friends and family know that, we might not let all children who visit us play with it. After hearing several stories about TVs being damaged by flying remotes, I am careful about who I let use my Wii. Saying it's boxed up and then not unboxing it is much easier (and nicer) than saying I won't let your child use it because I'm afraid he will damage something.
A few things jumped out at me from your original post:
All weekend long SIL was a basketcase and made everything miserable. She started out the weekend telling me how the other brother and his family had come to visit a few weeks earlier and she did not like how noisy their 5 and 8 year old kids were. SIL has a 2 year old son so should be used to noise, right? So I knew right then the weekend was not going to go well since we have a 6 year old and a 9 month old. My 6 year old can be a handful but if he has something to do, he can keep himself busy and out of trouble. That is where the problem came in. She did not want our 6 year old to play with any of the 2 year olds things. The only thing he was allowed to play with were 2 balls and they were only to be used outside. He tried to ride the hotwheel, and she did not want that. He tried to play with the dog, she did not like that. We had brought some Wii games for him to play knowing that they had a Wii and they just said it was boxed up and never unboxed it so that my kid could play it. The poor guy was going crazy!
She constandly was cleaning and fretting about something. She stood in the kitchen and proceeded to wipe up any drop of water that touched the floor. Cleaned up any toys that they let my 9 month old play with before she was even done playing....it was just miserable. I was a stressed out mess trying to keep both my kids quiet and in order so that she did not get upset about it.
We ended up only staying one night (a 3 hr drive both ways) because it was just to much. I just do not understand why she would ask people to stay at her house if clearly she did not like people in her home.
What makes me most afraid is that we are all (all 3 of our familes) are going to WDW together in December and I cannot imagine what she is going to be like then. We are staying in a 3 bedroom villa at AKV and she is just going to have to sit in her room and freak out because I am not going to keep my kids quiet at Disney. They are going to be allowed to get excited. I know that the other SIL feels the same way. Our kids get so excited when they are together and I am not about to hold them back because this SIL cannot manage her stress issues.
From the bolded, I get the impression that you simply have different parenting and cleaning styles. Many parents don't allow their children to be loud indoors. Just because she has a child doesn't necessarily mean that she should be used to extremely loud children. The fact that you don't intend to keep your kids quiet at Disney World would probably bother many people. In a shared living situation, especially a hotel, it's considerate to keep your voices down. If you don't intend to do that, and she does, that's not going to end well.
I wouldn't want some children playing with my dog, either, so I think it was totally reasonable that she didn't let your child play with her dog. Maybe her dog has aggression issues, or maybe it is afraid of some children, or maybe she thinks your child would be too rough. Whatever her reason, it wasn't rude for her to tell your child not to play with the dog. Since she invited you to stay with her, I think it would have been polite for her to have a few age-appropriate toys on hand for your child, but I really think it's your responsibility as a parent to travel with things to entertain your child,
especially since you say he can be a handful. Knowing that he needs to be kept occupied, you shouldn't count on other people providing things to occupy him. You should always come prepared in case they don't.
As for the water thing, that is a bit odd. Maybe she thinks it would damage the floor, or that someone would slip on it. Or maybe she's a little bit OCD. But if she wants to keep the water off the floor, then I don't think it's rude for her to be cleaning it up.
If it's possible, I think you should try to figure out alternate lodging arrangements for your trip. Your families don't sound like they mesh particularly well. If that isn't possible then you need to find a compromise that will work for both families. That may mean you will have to be neater and more quiet than you otherwise would be, and she'll have to put up with more noise and mess than she would prefer.