I bought this from Larry this spring, thanks Larry, and have been using it quite a bit so I think I can give you a qualified answer. Two up top is spacious, three could probably be worked out but would not be very comfortable and I don't see how four would work at all. With that being said though, if you use the walls the kids could sleep downstairs and the adults upstairs. I have set up the walls and they are very easy to use. Picture a queen sized bed and that's how wide the 1600 is, maybe an 1800 might possibly work for you.