I alread wrote about frankfurt office a while ago. Now I can tell about Sofia office. It is really wonderful. It makes you think about relocation just because of office (:
Office design looks really smart. Moreover the view from the office window truly increases your performance. It is always nice to think about complicated stuff while looking on beautiful mountains :)
Though if you really need some privacy you still can just go to the special terrace to "get some fresh air" (:
The office is a usual open space. Though I would make space delimiters a bit bigger.
From the other side you can watch the airport. Plane take offs and landings are cool for meditation. Though you have to do your job in between meditation sessions anyway and do it in time (: