My daughter and I booked the Pirin and Rila mountains guided tour:
http://www.bulgariawalking.com/p114-Hiking-trek-in-the-Pirin-and-Rila-mountains-guided-hiking-trek-in-Bulgaria.
A well organized and well thought of ,a great friendly good English speaking local guide - Lyuben Grancharov , 11 charming hikers from all over the world: Australia, Sweden, Israel, UK and Italy. It was a week to remember. Not to mention the Bulgarian food and drinks, the culture.
The contact person Ivalio from Traventuria was very helpful at the early contact stage in Emails - every bit of the program was fulfilled.
I highly recommend Traventuria,those guys are professionals.