Recently, my husband and I were on a flight and 'owned' the middle and window seats. However our neighbor in the aisle seat was severly overweight and took up not only his seat but the middle seat too, while we shared the window seat. In other words, we paid for 2 seats, but got to sit in one, while he paid for 1 seat, but sat in 2.

Okay, so we are now wondering if it's possible to purchase an additional seat (we would buy 3 seats instead of 2). There are a few of reasons for this:

1) To avoid the above situation again--it made for a very miserable cross-country flight on Christmas Eve

2) To gain extra baggage allowance (we are planning a big move overseas, but are doing our best to avoid shipping things)

3) To give ourselves extra room on long flights--buying a 3rd ticket is often times cheaper than buying business or first class tickets for 2.

So, has anyone done this? I guess another question is, if we were to buy a 3rd ticket, how would we go about checking that seat in--since Mr. Middle Seat doesn't have a valid photo id!

Thanks!