Anyone aware of cheap parking within walking distance (like maybe 6
blocks or so) of Sheraton Inner Harbor in Baltimore? (Just want to dump
a rental car there for 3 full days while at a meeting.)

[Or, is anyone aware of any better solution for 3 day stay coming from
the West Coast?

Hertz, Avis, and Budget all have offices within a few blocks of your hotel.
How about giving the car back when you get there, then rent another one
when you leave? It doesn't look like there's a drop charge from IAD to
Baltimore.

R's,
John