I have a small house and not much space either of wall or floor or furniture for that matter. I do a lot of layout on top of our queen bed, it may be hard on the back but it's easier than the floor! Currently I have one of those extra large cutting mats, or I've used heavy brown paper rolls (gotten at school supply store). Obviously this works well for small projects, not so good for larger.
It's an issue for many of us. I've been using a friend's long arm set up for my larger quilts for the last couple of years, but it doesn't look like it will be available for my use this year, so sandwiching is again an effort. I've been thinking of putting up an ad on Craig's List hoping to find a home machine I could use and for which I would pay, if for nothing else but to sandwich and baste the tops together. I feel fairly confident though that in my area there is someone relatively nearby who isn't using their machine as much as they thought and would like to get some return on their investment.
Many fire houses, libraries, or other public buildings have rooms (and those nice large tables) for public use. Sometimes a small fee, sometimes all you have to do is ask. I know some people who have access to their church halls, or who are school volunteers and use lunch rooms. You might also see if a large local nursing home or senior center has a community room, my friends belong to a guild that meets in such a place.