To answer my own question, I went to both locations this past weekend.
Beverly Hills was definitely the better option. I spent about an hour there and only 1 other person showed up the entire time. On the other hand, Century City is an open air mall, so there's a lot of foot traffic and more people stopping in to check out the car. Being the service center too, BH was a huge space to check out the car and VR simulator. Much airier (no pun intended) than CC.
BH has an exterior GT shell in black to see what the production model will look like, as well as a beta model with the Tahoe interior. CC has a preproduction GT in zenith red with the Mojave interior.
I can say I was quite impressed with the fit and finish of the interiors and it solidified my intent to get the car. I'm 6 foot and there was about 5 inches in front of my knees when sitting in the back seat after adjusting the front seat. HUGE!
Now, trying to decide between T and GT. If only they'd post the cost of the options...