One of the biggest considerations for resale value is the size of the house. Find out what the average size of a house is in your area and then slightly exceed that square footage. If you make the house too big you will price yourself out but you should know that people always want "just a little" more than what the Jones' have. So, you want to make your house just a little bigger than the Jones'.
Certain rooms add more to the resale value than do others. For example, a finished basement is a finished basement. There is not much you can add to your basement to really increase the value of your home. On the other hand, a kitchen is not just a kitchen. Kitchens are big selling points for homes. You might want to splurge on the materials used in the kitchen. Marble or granite counter tops will greatly increase the value of your home.
Consider your heating and AC systems. Radiant heating and central air are two feature that are guaranteed to increase your resale value. Building these features in from the start is the only way to go. Even if you heat the home with radiant heating, you may still want to include a fireplace (or two) into the design of your home. Maybe not in Phoenix but in a lot of other areas, fireplaces sell! Consider a fireplace in the master bedroom as a very romantic feature.
Start thinking about landscaping early. Little trees are inexpensive and easy to plant and they grow to be big trees. Big trees sell houses. What you want to do is get those little trees in the ground early enough that they will be big trees by the time you are ready to sell the house. When a person comes to look at your house they will first notice the landscaping, consider hiring a designer to design the landscape around your house.
Bathrooms are another big seller when it comes to your house. People want big luxurious bathrooms that feel like spas. This is not an expensive effect when you are designing the house but it will be invaluable later. Even if you don't use radiant heating in the rest of the house you can use a small electric heating pad to add radiant heating to the bathroom. Whirlpools and spas also are also excellent investments when you are designing your house.