I think it's smart to try concorde one way and first class the other, if you just wanted to try it before it is retired.

Nearly everyone I know who does this though, wishes they had just done first class the whole way. They all rave fondly about BA first class on regular planes, but say the concorde was a spartan let down. If you want a premier flying experience, concorde really isn't it, but it's handy if the shortest flying time is critical.