I would agree with the other poster and use wegoshop or garden grocer to have the groceries delivered. It isn't very expensive; you would save cab fare; and you save time. Even if you are not at your room when the groceries are delivered, the groceries can be stored (refrigerated and frozen, if needed) until you return to your hotel.
If you are doing this with another family, you can spread the cost of delivery between you. You just need to have your grocery list ready before your trip.
Have fun!