Annapolis to Baltimore is an easy run. We do it on avg in 3 1/2 hrs but that's at 7.5 to 8 kts. You can figure your time accordingly. It certainly wont take you 10 hrs. Inner Harbor East runs $2.10 a ft and is very convenient to Fells Pt and Inner Harbor. Their facilities are presently in trailers. They have showers although nothing fancy. The only advice I have for running the Patapsco is to keep a sharp eye out for floating debris. With all the shipping piers there's always something getting knocked into the water. Some of it can be rather large. Have a good trip.
My wife and I just made reservations to stay at Inner Harbor East this week and found out the dockage is free Tuesday thru Thursday!
They did say they charge for electric, ($8 a night,) but that we can live with.