I've managed to end up with a very, very nice (and expensive) oak floor frame that adjusts to different size quilts, a floor style PVC pipe frame, a smaller rectangular PVC pipe frame for lap quilting and an inexpensive round frame.
In addition to the space issue, I find putting a quilt on the large frame a bit of a hassle. It is much easier to "snap" a quilt into the smaller and less expensive frames. There is something relaxing about sitting in a comfy chair and quilting so I prefer using the smaller PVC pipe frame of a round frame.
You can get both types of PVC pipe frames via Joanne's Fabrics. I used a 50% off coupon and got the smaller frame for about $9. I would stay away from the really flimsy round wood frames and invest in one of the sturdier plastic round lap frames--especially if you have kids around or a bit klutzy. (Someone sat on mine and broke it!)
If the project is square, the PVC lap frame seems to be my preferred choice. If I am quilting a round motif, I switch to the round frame. The smaller frames are so inexpensive it's not a bit deal to have both.