Baltimore cruise port parking is generally easy and convenient. But I've only been there when there were two ships home ported (which is almost all the time). In December, a third ship will be using the port. So, parking may not be as easy. Check out the boards in September when a third ship will be there to see what is different and how it is going..
Also, when coming from the north, you need to use the right tube of the Fort McHenry tunnel as the exit is soon after you come out of the tunnel.