Parking web sites
Spot Hero Has SELF PARKING FILTER. No built in Map.
Park Whiz does NOT have SELF Parking Filter. ParkWhiz has built in map though.
Google maps Parking Locations
33 Arch Street Garage at number 33 Arch Street (0.18 miles) https://www.lazparking.com/ (10 floors?)
Pi Alley Garage at 275 Washington Street (0.19 miles) https://pialleygarage.com/ (avoid elevators 10 floors?)
Center Plaza Garage located at 75 Somerset Street (0.25 miles) Stairs, looks good to me. This one looks best. Less Floors. TD Garden Parking, wider spaces, etc.
http://www.centerplazagarage.com/