How to get three seats for the price of two on a plane

My husband's travel agent had this amazing idea that worked the last time we flew. Maybe everyone else already figured this out but it was a new idea to me, and a very brilliant idea at that!

So normally when I book seats on a flight for me and a friend/husband, I'll book them next to each other. Of course that leaves open the window or aisle, which will be snatched up first by other flyers.

Instead, when you book a flight you should book seats A and C for you and your travel companion, leaving the middle seat open. If someone does book this seat you can surprise them and tell them you'll give up the aisle so you can sit with your companion.

But no one will book the middle seats until all the aisles and window seats are taken so you are greatly increasing your chance of getting a free seat between you and your companion to spread out a bit more and be more comfortable on your flight.