I would use a tan with creme trim. This is a basic color scheme that goes with almost everything. This way you can appeal to the largest number of people. The photo's below are a couple of houses we recently painted with these colors and it looks good.
For added color the front door or shutters can be an accent.
You don't want a flashy color scheme. Plus, what if the potential buyer doesn't like greens or blues. Basic earth tones are the easiest to use and appeal to the most people.