We just did this a month ago and it was great. I liked going on our own because the guided tours didn't allow you to spend the time I wanted at certain stops.
Also the Cheers Bar is right there at Boston Commons where the Freedom Trail starts.
If you really are short on time you can take the Old Town Trolley they have and do a whirlwind tour of the Freedom Trail. This is also a good option if you don't want to walk a lot.