You can search for lively past discussion on this very topic, seems to fragment into those who always stay at RC and love it and defent it passionately, and those who stay at the Pen (or want to). Pen prices vary a lot seasonally or even by day of the week, generally it costs more than the RC. My own opinion is that there is no comparison, the Pen is better and I would even claim far better. But I attach very little value to the "all you can eat buffet" that comes with the RC Club floor, as I prefer to be more selective about what calories I consume, where and with whom. I would pay double to stay at the Pen over the RC, but that is just my opinion and not universally shared. But to put this choice in perspective, I'd say that both hotels would make the "10 best hotels in the world list" and this is probably the best RC in the world (while the Pen is definitely the best Pen in the world, really makes you wonder about the US operations being so poor by comparison).