Bees will visit pollen sources within 2 miles radius of their hive.
Before setting up hives, make sure you know what's within those two miles. Access to high levels of pesticides will contribute to your bee colony's failure. Recent studies confirm exposure to nicotinoids disorient bees and may contribute to whole colonies disappearing in what's been generally called colony collapse disorder.
On the other hand, if you want to treat your bees to favorite sources of pollen, scientists have also determined bees prefer plants in yellow and blue tones, such as perennial Midnight Blue Salvia, which are long blooming and will re-bloom if spent blooms are removed.
One of my honeybees has found salvia planted close to the bee hive.