The J W Marriott at the Mall of America, Bloomington, MN (not far from MSP airport) is supposed to be officially opening very soon.

However, please don't plan to arrive by private vehicle. I drove past the place a few days ago and only taxis and shuttle vans are allowed within about a block of their front entrance, although they did have a two-block long line of waiting taxis.

AFAIK you really can't/shouldn't park overnight in the MOA's regular free parking (in covered parking structures connected to the Mall). The Radisson Blu at MOA offers their guests a choice of valet parking or expensive self-parking in their own garage. It's not obvious what the arrangement will be for the J W, but I hope that they at least have some dedicated parking area somewhere for overnight guests.

BTW, there's a light rail station underneath the MOA with direct service to MSP airport and downtown Minneapolis. You can transfer to the new line to St. Paul.