I do prefer knowing about visits upfront, as my living room is "lived in" and often has crumbs on the sofa and floor as well as dog and cat hairs, so I prefer to clean that up for visitors.
I've never had a problem with asking guests to leave - you can formulate it nicely like "I think we need to continue this conversation another day", "I am sorry folks, but I really have to go to .... bed, shopping" etc. Don't just drop hints and hope they are noted. I feel that a lot of issues arise from miscommunication. Say clear that time is up, there is no need to hide it behind hints and you will be surprised that most people will be happy as they know what is what - very few are offended by it.