We also went through this "process" in the last year ourselves. My oldest son, his girlfriend and my grandson moved out Jan. 2010. I even waited 5 months before redoing the extra bedroom for my own studio, "Just in case". I had it to myself for 3 months and was so spoiled!
In Sept, they split and son moved back in. Now he is still here and grandson spends every other week with us plus we babysit for her when it's her week too. So, it is rather hectic and I sure don't get much time in to sew. But, I wouldn't trade it for anything.