The merits of paying off a mortgage with a credit card are discussed here:

http://creditcardforum.com/blog/pay-...h-credit-card/

If it costs you $25 for every 1000 miles you earn, it may not be worth it. However, if you do not have enough monthly spend aside from the credit card to hit the minimum spend bonuses for getting a new card (such as spending $3K to earn 50K miles on various AA cards) , and you have not pursued such bonuses recently, it would make sense to spend 2.5% or $25 per 1000 in spend to pay off 10-30K of the mortgage using a variety of credit cards that you get over a period of months.

This strategy could easily yield 500K in miles and hotel points over the course of a year or two.