I see nothing wrong with having a party in a hotel room at night as long as people are respectful. It's not like the OP wants to start a frat/sorority party where it's all wild and loud. I have a friend who does a yearly room party at a convention that's coming up next weekend. He reserves two or three rooms and people come in and drink and have a good time. He hasn't really had any problems and people are friendly and respectful, for the most part. There are some bad apples, but they end up getting kicked out. Room parties are going to happen. They happen at many conventions. I've been going to cons for 11 years and counting and stayed at the host hotel for anime/comic conventions and I never fail to see at least one room party.
That being said, there's nothing wrong with not wanting a room party.

I wouldn't mind going to a hotel room, sit around and have a few drinks and chat. I don't drink much. Usually have a drink or two as I am a lightweight, but I enjoy being sociable when I'm not being super awkward and shy. I also don't mind going to a bar if the room party doesn't happen.