at today's exchange rate, the difference in price is only about $86. I personally would not use this small of a price difference to persuade you into staying in one place over another.

If you appreciate the finer things in life, I will add my vote for the Pen. IMHO, the 2 properties are not even in the same league. The Pen is consistently rated as one of the best properties in the world, and is almost always in every top 5 list for Asia. The Hyatt is not even rated by any major publication AFAIK.

It is quite true: you will NOT be walking anywhere from the Pen. That being said, the boat service is very convenient and runs up until approximately midnight. For those late nights you're sure to have, a taxi to the Pen from almost anywhere in Bangkok will generally cost less than 250 Baht. Even if you get "hustled" like most tourists, taxi fare will cost no more than 500 Baht, which is about $14. You'd spend more money getting from the Mandalay Bay to Bellagio in Vegas.

To me, any way you slice it the Pen wins over the Hyatt. Now if you were considering the Oriental, Sukhothai, or Shangri-La there would be a lot more debate.

Also, I would book through Virtuoso. It will cost you nothing and will almost surely score you:

1. An upgrade
2. Free breakfast
3. Potentially a discount