I would love a system that gave me a single source summary of all hotel, airline programs and give me the option to calculate a vacation. For example, 'Go to Walt Disney World for 2' and have it search all my accounts and spit back something like that if I use 50,000 miles out of my UA account, and 8 of my 10 upgrades (2 each way per person), and XX of Hilton points to stay at the Hilton at the Village Marketplace and that the cheapest rental car that I have a membership card to is XYZ.

Could get very involved, but I'd certainly pay for it.