Quilt on the lap is why I love quilting in the winter, I can turn the heat back! The downside is that the cats like the lap in the quilt and want to join in the fun!
For big quilts I roll/fold the quilt. The only method I've found to keep the roll together is big binder clips. Otherwise I pin the bejesus out of the quilt and then make sure the section I'm working on is flat and just take my time.