If we're staying in a condo with a free washer and dryer, I'll do laundry. If we're in a hotel and we need the clothes, I'll do laundry. I prefer not to do it if I have to pay for it.
I have two laundry bags I take on vacation, one for whites, one for darks. We put our clothes in those in the hotel room. We put all the dirty laundry in one suitcase. It makes much easier to unpack, sort and wash. I start on laundry right after we get home.
We went to WDW in December one year. We didn't take enough warm clothes so I had to wash. It cost me a lot of $$$ (and time) to get those sweatshirts and jeans dry!!!