Pen BKK is my #1 worldwide. Stayed on last two visits to BKK--earlier this year and in 2007. Service and accommodation--grand deluxe suite both times--were excellent. iPod dock set up in advance for my visit (compensating for lack of up to date technology); though no one has mentioned it, the integrated bedside light, a-v and hvac controls are great; wait for cross-river boat never more than a few minutes; badly jet-lagged request at 1030 pm on the night I arrived in 07, "where can I get some street food?" was handled candidly and accurately (I now know in hindsight).
Finally, as I tend to dress down quite a bit in SE Asia (as much to keep cool as any statement about informality), it would piss me off to stay in a place where I sensed even the slightest condescension based on my appearance.
Anway, MfromT, love to hear about your relative experiences at the two places.
--mcz