We have not yet used them, but plan to do so in the near future. Based on work that I have seen and the experiences of several people I know who have used them, I would not hesitate to recommend Da Vinci Design Group. They specialize in older home renovations and additions, but work to maintain the style and quality of the existing home, as well as the others in the neighborhood.
A co-worker just finished up a huge renovation (adding rooms, renovating existing areas), and loved them. It was an 8-month project, but they were there when they said they would be, and managed their subcontractors appropriately.
Here's a link to their website:
http://www.davincidesign.biz/#/home.htm
They probably won't be the cheapest bid you get, but they will definitely do the best job.