Day 2) Golden Triangle + Doi Tung then travel to Mae Salong for overnight is quiet doable, but I'd suggest an early start so you get to Golden Triangle early morning so can get to Doi Tung early afternoon.
Day 3) Have the morning exploring Mae Salong then travelling to Chiang Mai for early to mid-afternoon ok. However it does not leave you with much time to do more than 1 activity such as The White Temple. I could be wrong though.
Here's my standard 3 days in Chiang Mai suggestions....
see map: http://goo.gl/maps/bAO9x
Day 1 - walk round the old town and see Tha Pae Gate, Wat Chedi Luang, Three Kings Monument, Wat Phra Singh, and finish at Wat Sri Suphan (you may want to get a tuk tuk to here). In the evening go to the Night Safari, you can catch a free mini-bus near the Tourist Police at 19:30.
Day 2 - I'd suggest hiring a scooter. In the morning (9-10am) go up to Wat Phrathat Doi Suthep (you may wish to stop at Huai Kaeo Waterfall on the way for a few photo's). Next go to Phu Phing Palace (Royal Winter Palace) for around 1pm and enjoy the beautiful gardens (respectful clothing i.e. long trousers can be hired there for 30B). When you're done (after about 2hrs) continue further in to the mountains to Hmong 'Hill Tribe' Village. In the evening grab dinner at Sila-aat Restaurant in the Night Bazaar and then go to the boxing at Loi Kroh Boxing (about 400B).
Day 3 - Go to Mae Sa Elephant Camp. Trekking optional extra. There are 3 shows a day and will take about 90-120 minutes. There's plenty of other things to see and do in Mae Sa valley so why not pick something else to do whilst in the area. Every Sunday there's a famous Night Market from Tha Pae Gate in to the old town, spend a couple of hours shopping before it closes shortly after 10pm.