Every person has a different answer to this. You appear to have a goal of a trip to Europe. If you have enough miles, most people would tell you to go business or first. I use my miles for long haul international first class trips that I would never be able to afford without the help of miles. Last summer I flew CX first class to Australia for 140,000 miles. Best use of miles I've ever seen. I also once used TWA miles for a next day STL-BOS ticket to see Pedro vs Clemens at Fenway in the playoffs. The ticket would have cost $1500, but it was mine for 25,000 miles (and no expedite fee). I love the Red Sox, but I'm not going to spend $1500 to see them. Both of these uses of miles were great deals to me. The bottom line is, if you are happy with the end result, and you feel like you got a good deal, then you probably did. I would never use 25,000 miles for a $350 ticket, nor would I use 40,000 miles for a $500 ticket to Europe. But if that's what would make you happy, then go for it.