Now here's something I didn't expect to have happen, and why you should probably wait to combine your accounts if you're able to.
As some of you know, I'm planning a celebratory trip to San Francisco in a couple of months. I have 3 properties booked for the same dates at the moment as I try to figure out which one to stay at. All are Marriott brands and I'm thinking of adding a 4th property to the mix, which is the Westin St. Francis.
Unfortunately, when I try to book the reservation (cash), Marriott.com kicks me over the SPG.com. And, when I attempt to finalize the reservation, I get an error message saying I have an invalid SPG number.
So I try logging in with my new and old SPG numbers, which the system will not allow me to do because I've already combined my accounts! As a result, it appears the only way I can book this reservation is by calling into the reservations line. And even then, when I call the SPG number now, it kicks me over the Marriott Reservations. And they usually tell me they can't help me with SPG reservations so they'll need to transfer me over to Starwood Reservations!!
Seriously, Marriott. Get your act together. These "glitches" are getting really old, really fast.