Singapore and Thailand - Must See's and Do's?

Hi all!

I am off to Singapore and Thailand in 40 days (not counting or anything) and I am starting to get a list together of things to do in each place. I am going with my best friend so it's very much a girly, relaxed, fun holiday. Just wondering who has been to any of the places below and if you can recommend things to see and do!!

Singapore
Phuket
Phi Phi
Krabi
Koh Phangan
Koh Samui
Bangkok

We just booked in for High Tea at Raffles in Singapore (exciting!) but that's all we really have locked in!

Your help is much appreciated!

x

Bangkok - shopping! The golden buddha temple, the grand palace, the night markets.
Phuket - the elephant safari, the long boats to phang nga bay.

That's all I can think of off the top of my head.

Bangkok - I had tuk tuk driver offer to take me to all the sites as well as his cousin's suit shop. Apparently there was a 'special' deal on just for that day :) I got great value out of it, apart from buying a silk suit I didn't need but did wear. But you dont have to buy. I did see the reclining Buddha, the palace etc
I hated Koh Samui. The girly bars etc depressed me. I did have a great Thai massage though
I loved Kanchanaburi & stayed on houseboats on the River Kwai - it was so peaceful. I wish I'd gone further up to Hellfire Pass. I did an Intrepid tour for that bit.
I'd love to have gone to Chaing Mai

Dh recently went to Singapore - the Long Bar at Raffles for drinks, dinner at Little India & shopping on Orchard Road. Check the dress code at Raffles before going.