I think the answer depends on the situation. I have more miles than I will ever use so I would tend to use miles. I tenD to upgrade with miles or money towards the end of the year in order to push up my mqms. I would upgrade rather than hoping for a free upgrade because that route can be and often is full in first. Older people willing to pay because they don’t fly often and need the comfort a family or two off to dis. So if you have the miles or money I wouldn’t wait unless you really don’t much care.