Have booked lots of award tickets, usually for transcon or trans-atlantic or upgrades, usually months in advance, and almost always had problems getting time and dates I wanted. Have had my poorest success with Friday afternoon/evening and Sunday evening. Not sure I have ever been able to get a Saver Award on a DEN/SEA leg on Sunday evening.

Just found out this morning (Saturday) that I need to be in DEN next weekend. Some flights about $370, but would like to leave SEA Friday late afternoon/evening and return Sunday evening. These are pricing out about $460. Normally, I wouldn't use miles for a trip to Denver, but with some extra miles, and, at $460, it becomes a possibility.

Have never checked award availability before within a week of a flight, and didn't expect to find anything, but decided to check SEA/DEN availability anyway for next weekend. To my surprise, Saver awards (25,000) are available on almost every flight SEA/DEN Friday and DEN/SEA Sunday, including evenings.

My first question for those regularly booking late awards is: Is this normal? Does it happen with reasonable certainty?

So I am considering possibilities I have missed: when a flight has been booked some months previously, then it turns out the week before the flight that there are lots of better flights and routings now available on ALL legs. Then, I could have booked a new award flight at the better dates, then canceled the original award flight and paid the fee to replace the miles in my account.

My question is: If new and better award flights turn up a few days before the flight only on some legs, but other legs already booked now show no availability, is there any way to rebook, keeping the previously upgraded legs and adding the new leg or legs now available?

Seems reasonable to me, but am not sure that means reasonable to United.

Bruce