Oh goodness, you're in good shape and if you don't know when or if you will be coming back to China, take advantage of as much of the 60 day allowance as you can, the timing will never be better than the present. Please dump that Yangtze Cruise and make a new quickie plan. Let's say Day 0 is your arrival from JZG back to Chengdu.

Plan 1--Lazier Plan--Chengdu to Guilin area to SE Asia

--Day 1: Chengdu. Pandas in morning, Sanxingdui early afternoon, Chengdu city (like Jindi or Kuai Zhai pedestrian streets) late afternoon into dinner time. (Overnight Chengdu)
--Day 2: Leshan Buddha daytrip + an old town like Ping'le or Luocheng. Leave first thing in morning, return late afternoon. (Chengdu)
--Day 3: Dujiangyan Irrigation system or Chengdu City (Dufu Cottage, Wenshu temple) during day. Evening flight to Guilin. (Overnight Guilin due to arrival time)
--Day 4: Car or bus to Yangshuo in morning. Yangshuo area (Yang)
--Day 5: Relaxing in Yangshuo area (Yang)
--Day 6: Relaxing in Yangshuo area (Yang)
--Day 7: Car or van up to Rice Terraces area in morning. Afternoon walking around Terraces (Dazhai village area)
--Day 8: Sunrise and morning at terraces. Afternoon return to Guilin and either fly onward or stay overnight and fly to SE Asia next day.

Plan 2--Active Plan--Chengdu to Yunnan to SE Asia

--Day 1 and 2 same as above
--Day 3: Morning flight Chengdu to Lijiang. Afternoon Lijiang town. (Lij)
--Day 4: Baisha, Shuhe village/valley or Jade Dragon Snow Mtn Park. (Lij)
--Day 5: Tiger Leaping Gorge daytrip (if a hiker, can do an overnight and stay at the gorge). (Lij)
--Day 6: Lijiang to Shaxi village in morning, afternoon walking in and around the village and valley. Overnight Shaxi guesthouse.
--Day 7: Morning Shaxi to Dali via Jianchuan. Afternoon Dali. (Dali)
--Day 8: Dali area (Dali)
--Day 9: Bus (faster) or train back to Kunming. (Kunming)
--Day 10: Bus to Jianshui south of Kunming morning. Afternoon Jianshui (Jianshui)
--Day 11: Bus or car to Yuanyang Rice Terrace area morning. Afternoon Terrace area (Yuanyang).
--Day 12: Yuanyang Rice Terrace area (Yuanyang)
--Day 13: Bus to Hekou and Vietnam border, about 3-ish hours. (there are other alternatives such as returning to Kunming to fly elsewhere, or going overland to the Laos border crossing which is farther away).

Given your time frame, my recommendation is plan 2 but you may already be too tired. Many permutations can be done, like hanging out and relaxing in Lijiang or Dali, getting to Kunming, then flying onward to SE Asia from there. It's just a good time of year to travel in these parts, cool and not humid, and not too many tourists. I prefer Yunnan to Guanxi/Guilin Area, but nothing will be redundant with the places you've already seen.

Particularly if you want to fly to SE Asia, Kunming is the best place since there are nonstop flights to all the nearby SE Asian countries from there.

Note: if your intent is to cross to Vietnam overland, you'll need a visa in your passport beforehand (can't do the VOA thing). If you don't already have, Kunming has a Vietnamese Consulate but plan enough time at least to get a rush passport. Laos land border or fly-in can get VOA. Cambodia can get VOA.