The top floor in the garage always has good spots right by the elevator until about 10am. For rush hour, stand towards the end of the platform for more room. Get a SmarTrip card as well.
Park in the kiss and ride garage while you wait for your party. They can take bridge across to you, avoiding the elements. Plenty of free spaces daily.
Make sure you beat the morning rush by taking the train at least 15 mins earlier than your actual timeline. You can never tell what's going to happen to the trains that day.
Use the short term parking lot across the street to pick up. Passengers can walk across bridge to garage, staying out of the elements and it keeps the road clear for traffic.