I don't know that all of these comp opportunities are literally "once in a lifetime." That sounds more like airline marketing hyppe, then true reality. Of course, programs don't want you to think that it is so easy to get re-comped. I know for a fact, for example, that UA will comp more than once. And even if a program truly has once in a lifetime comping, you could always set up a new account say at your office address (assuming your original account was at home), get the comp, and then combine the two accounts.