Mountain Trader:

Some airlines websites (i.e Continental and American) tell you which routes are more likely to be able to upgrade in the upcoming month.

I agree with you, I stopped flying Continental from the UK to the US and Latin America last year, because of the difficulties I had trying to use my miles (over 100,000) for rewards. I have been Silver Elite 4 years in a row. Finally cashed them all in and gave my mother and cousin upgrades on a visit from Latin America to the UK, and said good ridance to Continental. I have switched to American Airlines.

My suggestion to anyone is to just keep one airline to accumulate miles. Keeping miles in more than one program today is not worth it. Find which are their partners and if you fly them bank the miles with your one airline of preference.