Only plan on staying around 10 days, missus loves to shop around and chill although me personally prefer the quiet relaxing areas with a decent hotel and restaurants etc. Would like to explore Bangkok, Phuket etc.
10 days isn’t that long to travel around too much but it’s possible , on most of my trips to Thailand I’ve travelled about but I usually stay for 16 - 20 days
Most of the bigger cities will have shopping malls with all the usual brands and some smaller boutique places
there’s a few areas to stay in Phuket , Patong is one of the biggest and full of nightlife but it’s not somewhere I’d consider peaceful , I haven’t really been to the other areas but Patong can be very rowdy, can easily visit Koh PhiPhi from Phuket via a regular ferry or speedboat, very small island but very relaxing and chilled atmosphere, not much shopping though
Hua Hin seemed a very relaxing city but I never really ventured far on foot as my missus drove everywhere so I probably missed a lot , also we stayed in very cheap accommodation so I can’t really vouch for any hotels or resorts
Pattaya is a bit similar to Patong with a big nightlife but it has a bad rep, there’s some nice hotels /resorts there though and plenty of restaurants and only a couple of hours in a taxi from Bangkok
Chiang Mai is a nice city and has a totally different feel , we went into the mountain area for a night and stayed in a glam;ing pod type thing , it was on stilts on a steep part but didn’t feel too unsafe , had a hot tub etc , was nice for a night just sitting at sunset with a Thai bbq cooking our dinner - probably best to fly here from Bangkok but flights are not much
Koh Samui was quite nice but not my favourite place although may go again and stay in a different area
Koh Chang - a trek getting here , 3 or 4 hours drive from Bangkok then a ferry but a very relaxed place, not much to do though but a few decent resorts just to chill by the pool
Koh Samet, need to get a speedboat from Rayong , cheap and very frequent , but like a bus service but boats! very very small island but nice for a few days just to relax
Bangkok, I love Bangkok , so easy to get about and tons to see and do, loads of shopping , loads of markets, great hotels and restaurants