the absolute best use of miles is getting the bw [beautiful wife] into c,j on over the pond flights[ either pond]. saves a lot on divorce costs.
for us , international ug's are the most desirable ...sometimes 6-8 cents/mi. when comparing disc coach to full c,j. 2nd is relatives domestic last minute gift tickets.
i just returned from a caribbean trip where i opted for 30k mi's instead of $900 [$825 after paying tax] [$775 after paying $50 to make the computer go to extra work to do it in less than 21 days]