Flexibility parlayed into a $350 travel voucher!

This a.m. I and the 2 students traveling with me were able to turn our travel flexibility into a $350 travel voucher! We arrived on time in PHX from DCA on USAirways, and when I went to query the gate agent for a seat with more room (i.e., EXIT ROW!), she instead offered me $350 if I would take the next flight (leaving 3.5 hrs later). I said I was traveling with 2 others, and if the offer would be valid for all of us. She said she wasn't sure but we could see. So we put our names down and waited for the boarding to finish. Sure enough they needed 4 volunteers to give up seats, and so the 3 of us are spending a few extra hours in Phoenix but now with $350 travel vouchers. The only other time this happened to me also occurred on US Airways, a flight from CLT to PGV (I've volunteered maybe a dozen other times to be "bumped", but in each of those instances the flight ended up not being oversold). Now, where to go on US Airways' dime....