i spent 3 weeks in yunnan last year. everyone goes to dali and lijiang and yes they are crowded. but here is how i still enjoyed them.
in dali stay outside the ancient town. i found a hostel near erhai lake. cheaper and quieter. rented a bicycle and rode around the lake. took me like 6 hours but i stopped a lot for photos.
the town itself is touristy but the food is good. try the bai minority food. there is a cheese thing that sounds weird but tastes great.
lijiang is worse for crowds. shuhe old town is just outside and much less crowded. same style but way fewer people. i stayed there instead.
the best part of yunnan was not the big towns though. take a bus to shaxi old town. it is small and quiet and feels like what lijiang probably felt like 20 years ago. no big shops. just locals and a few guesthouses.
also tiger leaping gorge. do the 2 day hike. it is not hard and the views are amazing. you can stay in a guesthouse on the trail. they have hot showers and good food.
yunnan is big. do not try to see everything in one week. pick 2 or 3 places and take your time.