We almost never avail ourselves of laundry services even if they are offered at the places we stay. My wife and I carry three sets of under clothing and socks which we rotate. We wash each evening which gives us a change for each day and an emergency pair of everything. That takes little space in our luggage and does the trick for cleanliness and comfort. We then add in a pair of shorts or two, a pair of long pants, a sweater or jacket (depending on the weather), a couple of short or long sleeve shirts as needed, comfortable shoes and flip-flops for the shower or occasional beach visit. If you have special requirements or interests, you should have plenty of room.
Our single piece of baggage leaves for the trip almost empty except for the items listed above. We augment the luggage with a small toilet article bag and my camera equipment. Since there is frequently an absence of available medicines in some of the towns we stay in, we take bandaids, aspirin, a general antibiotic and an antibiotic cream, an anti-itch cream, cold pills and lozenges, insect repellant, sunscreen and wipees (clean water is not always available) and tissues. We add on any medicines we take regularly. Make sure to carry these with you if you send any luggage through on a plane.
What do we do when we need to dress up? We almost never face that problem. We have found that hotels and restaurants will take our mastercard no matter how we dress, we look at least as good as the people we are visiting, and we don't expect to see the people we meet ever again so making an impression is not a goal. Keep it simple, light and convenient. One additional tip is to leave enough space when you depart for picking up some of the wonderful artifacts you will encounter. On the way home, we send our remaining belongings (the stuff we don't throw out) home in a bag and carry the things we purchase in our luggage safely packed for our enjoyment upon arrival. Happy travels.
Tibetan Woman Spinning Wool