Congratulations on your marriage in Phuket !
there are lots of tours on offer in Phuket and Bangkok. Depends what you like and you can just walk around, compare prices and choose a tour that interests you. Most popular is snorkelling trips, diving trips, kayaking trips (John gray is very popular), island hopping trips. If you fancy nothing then there is nothing better to do than to relax at a nice beach and enjoy the scenery and each other's company.
Hope all goes well and you have a good marriage life ahead