The best sort of day to me is a rainy day. A pleasant warmth suffuses me as I look out the window to see gray clouds and hear the sound of steady raindrops. Does this mean I'm missing a gene or something?
You hear often about weather-related depression...I'm the exact opposite. I get depressed when it's gorgeous outside, usually because it means I miss out on the beauty of the day, stuck behind a desk for 12 hours.
Things that make me happy: putting on my jammies at 6:00pm and cuddling up on the couch with warm blanket and a good book, the warmth and light and good smells of the kitchen against the gloom outside, eating pancakes for supper on dark, stormy nights, and hearing the sound of the rain hitting our bedroom windows as I drift off to sleep.
Cozy days are soothing. They force a person to relax, there's no yardwork to be done, running errands ends up being a pain-in-the-rear, so it's easier to just lay on the couch, hour after hour.
After an entire weekend of that, I'm a very happy girl.