Sorry, I'm having a bit of trouble mentally processing your posts.
I haven't been to Phuket in over a decade but Karon and Kata were nice quiet areas in 2003.
You mention Myanmar in regards to Chiang Mai. You can fly over to Mandalay, spend a day there, then take a bus down to Bagan and spend a couple days there. From there you have two options, go back to Mandalay so you can fly back to Thailand OR continue down Myanmar. Inle lake, Yangon, then fly back to Thailand from there. Yangon has several international connections so you could also continue to another country. Also you will need to purchase and acquire a visa for Myanmar.
If I do 7-10 days in Phuket before Chiang Mai anything on the way or return to BKK?
I don't really understand this question. You just fly from Phuket to Chiang Mai.