Since you'll probably know the dates of travel in advance for these, you can buy leisure tickets in the $200 - $250 range. So, using 25,000 miles for such a ticket puts the value of the miles at 1 cent per mile.

I suggest fogetting the mileage credit card and getting a cash back card that pays straight 1% back, no annual fee, and pay cash for the trips.

Essentially, you can earn 1 mile per dollar and get a free ticket for each $25,000 you spend on a mileage card. Or, on a cash back card, you can earn $250 for each $25,000 you spend, then buy a ticket that also earns miles for flying. If you fly enough, he can even earn status on the airline, allowing more benefits and miles to be earned.

Many cash back cards tier their programs (first so many K get 0.25%, and it increments up thereafter) and makes you wait til the end of the year to claim your cash. BankOne/FirstUSA has a no annual fee Free Cash Rewards Visa that gives 1% cash back on all purchases (no minimum), and you can claim your cash each time you accrue just $25 in rewards.