Yes, the NYC Marquis has an Elite Check in area, as do most West Coast Marriotts, though some put up the signs and lanes only during rush periods, such as after 4 pm, and take it down after 6 pm. The Marriott Marquis at Times Square is always open.
I've suggested something different to Marriott: RFID cards embedded in both Platinum and Platinum Premier IDs that automatically can be read as you approach the check in, and a machine to provide your keys.
If you've driven a newer Toyota Prius and had that rectangular key fob with the RFID device you know it requires no power to work and that it never fails. Grocery chains are experimenting with RFID tags on their shelve items that would debit the item from inventory when removed and put in a cart and allow paperless and personless checkout.
Rewards Elite Cards made this way could be time sensitive as well--not work at certain times, etc., an could be canceled by the hotel if they are stolen or lost.
Having a Marriott Rewards Card that actually checks you in would be a great advantage and first in the hospitality industry.