pinniped

Check-in at T-24 and you'll likely get a low B boarding number. This will get you your choice of aisle or window, likely in the middle part of the aircraft. Maybe a little better if it's a lightly-loaded flight; maybe a little farther back if the plane is coming from farther up in the northeast and has a lot of passengers remaining onboard. But as long as you check-in at the right time, you will not end up in a middle seat as a solo flier. No real need to buy EBCI unless you simply know you won't have any data connectivity at T-24.

Agree with ERAU...the process out of BWI will likely be rather sane. Since all pax are allowed to check luggage, you don't often run into situations where FA's are gate-checking a bunch of bags at the end of the boarding process like they do on some other carriers/types. When the system is working correctly, they turn around aircraft more quickly than most other carriers.