Originally Posted by chicagoariel

3. I find all of the rules for FF credits and awards really complicated (I suppose they want them that way.) Sometimes I'll find a flight cheaper on an airline I don't usually travel (usually one of the budgets, or through priceline or STA); what is a good "rule of thumb" for paying extra for a flight one is accumulating miles for? Say an ORD-SFO American flight is an extra $50 over JetCheap; will I generally end up ahead in the long run by paying extra to get those miles? How about $100?

For example, I was going to book a near-full fare ORD-CDG for $750; I found a deal through STA for $600 but it turns out the booking code is Q and there's no mileage credit for transatlantic flights on that code. Smart, or foolish?