I am in NL typically about 6 times a year and have done the W many times as well as REN and recently the Sir Albert...W is on the pricey side and I have had great success getting amazing upgrades there and i really prefer the bank building - its quiet and the brunch is really fantastic. its just a quick walk of you want to head over the the exchange for the 6th floor.
The REN is a great central locale and with decent rates, it is a great option. sometimes the length of time to check in is a pita but overall very nice.
I recently did the Sir Albert and amazing area (imho) and quite a nice vibe and the restaurant IsaKaya is really nice food and a great place to unwind. I was really pleasantly surprised, rooms were tighter than the W and Ren if that is a big variable for you but well equipped...and when in ams, no reason to hang in the room.