I agree that miles are sometimes difficult to use, but if you use a little creativity you will get great use out of them. I've burned through more than 500,000 miles in the last year (465k on NW, 35k on CO) and gotten $30k value out of these trips. (If I had purchased them directly)

It's quite important to plan ahead. I've burned 175k miles since December on awards that were going up (35k US-South American awards), and booked a number of rewards for next Christmas. These awards will be impossible to get if you wait a few months before you want to go.

I've never used miles for domestic flights, and use the miles for high dollar tickets. For example, you can book an Asian $3000 BC ticket (from NRT) for 30k miles.

It's always quite important to check partners for flights. Almost none of the airlines will list non codeshare partners when you check flights online. You chave to go the extra mile to check MH, Copa and other flights.