Remember, DVC is still a timeshare, and follows what most timeshare industry standards are. You will get a full cleaning on day 4 of your stay, and trash and towel service on day 8 if you are staying longer than that. Check-in day is counted as day one. A studio and 1 bedroom villa will each have 4 bath towels and 4 hand towels and washcloths. A 2 bedroom villa will have a additional set like that in the second bedroom. A 3 bedroom will have those two sets of 4 plus another one in the 3rd bedroom and a set of two each in the downstairs hall bath. Remember that if you are staying in a 1,2,or 3 bedroom villa, you will have a washer and dryer in your unit which can be used to wash towels should you need them in between T&T and cleaning days.
As MG said, we really prefer not having housekeeping. It's no big deal to make the bed when I get out of, just like I do at home. It only takes a few seconds. We always find there are more than enough towels, and often when the cleaning or T&T day comes, there are still unused towels.
You also can call and pay for an extra towel pack when you need it at $6 per pack of 4.