It probably also depends on how many miles you have. If you have upwards of several million, and it won't make a dent in your stockpile, then you'll definitely be more picky and "issues" with ua j could bother you. But if you don't have so many miles, and would therefore be spending extra instead of on what could have been a second trip, psychologically you're factoring all of that in, and you may not be able to enjoy all the premium comforts as much, because subconsciously you're asking yourself ''is it worth it?" at the "expense" of taking another trip.