My hair is past shoulder length and I wash it every other or third night, then blow it dry with a bit of thickening serum made by Chemistry and I think it looks really good.
I only do a ponytail when we walk the dogs or I am doing ward work or something like that.
WVJules, some nights I just rinse my hair with the shower water rather than washing it. I read recently in Prevention magazine it was not a good idea to wash hair every day. When I was working out hardcore, I did the more strenuous exercising 3 days a week, and weight training 2 days a week, so I washed my hair on the 3 days I was getting the most sweaty.