Also remember UP fares (QUP, YUP, etc) also book into A and depending on the market can be fully refundable and changeable with no fee. The key is to check the fare rules each and every time. Yes theres alot of text to wade through but there is also a short-cut. Just look at the Fare Basis Code. If it contains the letter "N" ie. H0NBV, it is non-refundable and there is a fee to change. In the same market (IAH-MSY) you'll find HUPBV which is refundable, no change fee, and the UP means it will book into A class when there are seats available in that fare class.