Up to Vihren and back, a full day out. Bring boots, water and a jacket — the weather turns above the tree line.
Doors open fifteen minutes before we start, and there is no need to arrive on the hour — people drift in. If it is your first time, say so at reception and someone will introduce you around rather than leaving you to work it out.
Everything happens in English unless the whole room turns out to speak Bulgarian, which does happen. Bring a laptop only if you want to.