I personally wouldn't heat only one room in a house in the winter, unless you live in a very warm climate and don't have to worry about pipes freezing.

In the summer though, I have not turned on the AC for the past several years. I set up a fan in my bedroom, aim it for the bed and spend most of my time at home there - wearing very little, lol.

Keep in mind on the swamp cooler - they are really designed for non-humid climates. I don't think they will provide much relief with high humidity.