You can get a 6 month tourist visa.With the extensions you can spend around 9 months. Then get in back without a visa and get 1 month + 1 month with extension. Then, get out and get a 2+ 1 tourist visa. That is like 14 months already. If you want to live in one place,I would suggest get an ed visa.
There is no point of going to Bkk for one day. You will waste your time in traffick and maybe eat one or 2 times, and go back to the airport. Even Phuket for 5-6days is nothing. I would choose one destination and it would probably be Phuket because it is a beautiful Island.
Just got mine today 500 bath on a tourist visa, took 30 minutes. But, It depends on the city too. And they might want to hassle you with the insurance for 7 k, but don't give up. Say you know many people who didn't pay anything. It worked for me in Hua Hin.