Day 1 -Phuket City tour – explore beaches,shooting arcade, snake park, mountain biking.
Day 2- Head to Phi Phi Island. Very beautiful and it is about 2.5 hrs from Phuket
You can do scuba diving,snorkelling there. Try to stay here [IN you stay,you’ll need an extra day]
Day 3 – Head to Phang Nga Bay [James bond Island] – Different experience altogether since it involves going through mangroves, canoeing etc before getting to the spot. One entire day needed
Day 4 – Head to Bangkok- Exploring the city for half a day. Then dinner cruise on Chaophraya river
Day 5 – Damnoen Saduak floating market, River Kwai and Tiger Temple
Entire day needed as it is far from Bangkok
Day 6 – Bangkok city tour includes visit to Golden Buddha and other monastries etc.
What you can also do –
Krabi and Phi Phi Island are almost same. Choose one
If going with friends, Pattaya would be better option.It offers a variety of water sports and beach-related activities.
You could also visit Chiang Mai – This mainly has monastries