DD and her two friends want to go to a comic book convention in Baltimore at the Convention Center July 19-22. They don't want to spend more than $150/night for a shared room, so I was hoping someone could suggest a nice clean hotel (Comfort Inn, Courtyard, etc) not too far out of town where they could have free parking and take a train or subway to the Inner Harbor each day. Any ideas? Thanks.

There are newer hotels near Arundel Mills mall which has lots of shopping & restaurants at the mall or surrounding the property. There is an Residence Inn & Hampton Inn adjacent to mall property.

http://www.arundelmills.com/static/doc_005749.jsp

One of the lightrail parking lots (free parking) is within 10-15 min driving. The lightrail will take them right to the convention center stop.

http://www.mtamaryland.com/services/lightrail/general/

I hope this helps

The Marriott at BWI Airport has rooms for those dates starting at $159 and free parking. They offer a shuttle service to the light rail.

Some of the other airport hotels may be even less expensive. It's a good area - not too far from Arundel Mills.

You can try Priceline. All of the 4* Inner Harbor are more than okay. Even after parking fee, you should still be paying less than $150.

I would go the Priceline route first. You can usually get a 4* Inner harbor hotel for your budget. That would be best because it is the most convenient and they can take in the charm of the Inner Harbor when they aren't at the convention.
If that doesn't work they could also try Owings Mills. There is an AmeriSuites and a Hilton Garden Inn there which are both nice. Like Arundel Mills, it is near a mall and lots of restaurants. The Metro (different from the light rail) is less than a 5 min drive. The Metro will take them within blocks (safe) of the Convention Center.
I don't know where they are coming from. Owings Mills is N of the city, BWI and Arundel Mills is S of the city.

I wouldn't ride on the Baltimore metro (subway) if it were free & you paid me. It's very unsafe & ghetto. Owings Mills is just the same thanks to the metro!

I stay at the Owings Mills Hilton Garden Inn to visit relative in nursing home. The Garden Inn is just fine. The Amerisuite is ok, kinda cheap furniture, but ok in a pinch.