I have a list of "don'ts" when discussing home upgrades for moderately priced homes:

1. Adding high-end appliances to a modest home.

2. Adding hand painted tiles in the bath or kitchen.

3. Adding a central vacuum.

4. Replacing windows with newer models.

5. Adding a swimming pool.

However, when you are dealing with luxury homes, people expect and are willing to pay for luxury. A swimming pool or a hot tub may be in order! 

The moral of the story? Keep the buyer in mind when you get a house ready for sale.