If I can offer you some advice, it would be to consider getting married somewhere outside of Phuket or Phi Phi as these are home to the most crowded beaches in all of Thailand ;)
Much closer to Bangkok is Ko Samet, or even Ko Pha Ngan's Thong Nai Pan Noi should be just a beautiful, but much quieter. Near Krabi is Ko Lanta which has some nice beaches in the northern part, and some great resorts too.
we got married in Phuket I have included some photographs - i live here and we had a buddhist wedding in our friends house and the celebration on the beach at the hotel I work for -
http://boards.modernbride.com/groupee/forums/a/tpc/f/77210611/m/29410559
