I don't nearly as much as I used to, now that the kids are grown. My granddaughter is two this year, though, so we definitely are planning on setting up all the lights and decorations for Christmas. We didn't last year, as it seemed too much trouble for just the two of us to bother.
I used to decorate for every season that came around. Like MakeDoQueen, I have cut back lots because I hate to take it all down and put it away. I love to put it all up but when the season is over, I wish I could just twitch my nose and make it all go away.
We decorate for all seasons. We have a ton of decorations for both the indoor and the outdoor. I love decorating and so do my kids. Every year when I decorate I end up donating a lot of decorations. If we don't use it every year I get rid of it.
I go all out for fall and Christmas. For the other seasons, I have a 6 foot tall rustic holiday tree that stays up year round and gets decorated for Mardi Gras, Valentine's Day, St. Patrick's Day, Easter, and then all three summer holidays.
The winter solstice brings out the interior decorator in me. All other seasons I couldn't care less about. Thanksgiving especially has colors associated with the decorations that I like to try and keep up year round. They make everything feel "cozy".