Ideally, you want your hive to be located in an area that is high and dry, with a good amount of sunshine in the morning hours but enough shade to protect it from the intense mid-day heat when the sun is directly overhead. If shade is not available, you may want to paint the roof of the hive (top only) white to reflect the sun's light and heat.
DO NOT place your hive in close proximity to any building. this will cause severe temperature swings that will make life very difficult for your bees.
Place your hive so that it is facing southeast, if possible, so that the bees will be stimulated by the morning sun coming in through the entrance.
Plenty of fresh water should be located nearby. You may need to supply your bees with water to keep them out of your neighbor's swimming pool.
The hive should be protected from the prevailing winter winds as best possible.
Keep the hive at least 12 inches (30cm) off of the ground to allow for some inspection of the hive through the screened bottom. Having the hive up this high also helps to protect the bees from excessive moisture, ants, skunks, snow, etc.
The hive's entrance should face a wide open area, but be directed away from places where there are likely to be people or pets.
Place your hives at least 4 feet (1.3 meters) apart.