Those are nice hotels, but they aren't world class or anything.... Thailand is a weird place for hotels and "resorts" - you can find very decent lodging for (well) under $200, and you can find really great places right at that # - but to get into the super luxe (aka what most would consider a true 5* experience) you pay out the ass. I believe the only genuine 5 star hotels in Thailand outside of BKK/Chiang Mai are in Phuket. The Banyan Tree is excellent from what I've heard, and I know from experience that the Andara is excellent as well (and a good deal cheaper than BT - but a lot more $$ than anything on Samui). The "5 star" hotels in Samui are nice though, but they aren't at that level really. The biggest thing though, is at the really nice/expensive places in Phuket you really don't ever leave the complex and it spoils you. Samui is a completely different type of island than Phuket and if it were my money I'd definitely opt for Samui over Phuket - the hotels aren't as nice, but its probably a better value overall.