In case you missed it, United recently announced a strict policy for dealing with overweight passengers. This has prompted two other airlines to clarify their own such policies, and it's no surprise that the airlines in question—Southwest and US Airways—are a bit more generous than United.
Here's US Airways spokeswoman Valerie Wunder: "Our policy is that safety and comfort are the main priority for all our passengers. We try to accommodate passengers at no charge first, by offering seat belt extenders or if there are seats available, offering them an additional seat. If the plane is full, we offer passengers of size accommodations on the next available flight with seats, again, without change fees, etc. Then if that is not an option we would charge the passenger for an additional seat and ask for volunteers."
Southwest spokeswoman Whitney Eichinger spoke about her airline's policy: "For those customers who occupy more than one seat, we do ask them to pay for that seat. We do offer the seat at a discount and refund the fare if the flight is not completely full."
I think these statements more or less speak for themselves, so I won't say much. But it's refreshing to see at least two airlines trying to preserve the comfort and personal space of their passengers without punishing overweight flyers by forcing them to purchase a second seat under most circumstances. It's not always easy to find a realistic and fair compromise, but it's worth a shot.