I just hit my 600 night with Marriott and I've been a loyal member for the last 10 years. I'm not one to complain but since the merger, the service has been awful. From the customer support on the phones, hotel staff, to parking attendants it's all going downhill. There's no longer the spirit to serve. No one is willing to accommodate anything it's been a real shock.
If you treat your faithful customers poorly then they will start looking for other accommodations.