I think there's some things to consider, and depending on what works best for you, you should go with that. Some people will not want to leave their neighborhood or homes on Halloween night - they want to be sure to stay up long enough to give out plenty of candy, or they have their own decorations they need to take down or bring inside. Also, some parents have their kiddos on a schedule and won't want their kids to be up so late to be AT a party with them, KWIM?
We do an open-house on Halloween night & invite friends, family & neighbors. We live out of state of most of our family, so attendance by them often depends on the day of the week or how old the kids are. We put our own kids to bed - later than normal, but not as late as we stay up. They will be 4 & 2 this year. Some of DH's family, who live nearby, don't come out to our house until after 10pm, because they give out candy themselves & prefer to wait until their neighborhoods are empty. Also, some families will come to our house and just use it as a home-base, but go out TOTing in our neighborhood & then come back for food or for the bathroom. LOL!
An open house is different than a party though, IMHO. We get a lot of people here but they all hang out differently. Some stay a while, some just pop in, others hang out at our fire pit while some prefer to stay inside by the food. While DH and I are trying to keep an eye on our kids, give out candy AND visit with guests AND keep the food & drinks stocked - well, we aren't exactly getting a lot of chances to really chat, you know? Plus, with people arriving & leaving at different times, people are always seeking us out and interrupting what we were doing. This is okay with us because it's the life stage we're in right now, but it's not the same as a party where you can really mingle & visit.
In your case, if you want to have a party, here's probably what I'd do - I'd host a party on a DIFFERENT night than Halloween, to ensure that most people could come. Then, I'd hire a babysitter to be downstairs with the kids, supervising what's going on, keeping them busy & entertained, and giving them permission to get snacks & drinks for the kids. Then I'd have the adults upstairs, knowing that the kids were being looked out for downstairs. In addition, I'd make sure that the parents knew this would be the setup, making sure that everyone understood it would be adults upstairs & kids downstairs, BEFORE the party started. Because some parents will want to keep their own eyes on the kids or won't feel as comfortable if they don't know the sitter. And some kids are just not mature enough to hang out without their parents at a new house. And if those families know in advance what to expect, it'll be easier for them to decide whether to come.
Good luck with whatever you decide!