One of the best things about visiting US national parks is the opportunity to sign up for wonderful ranger-led programs. A changing menu of options are available at Bryce's visitor centre, the best by far being the full moon moon walk. Activities vary greatly with the seasons, so check in at the visitor center to see what's on offer.
Rockheads will love the 20-minute geology talks, held daily at 11am and at 2pm at Sunset Point, which take you through the eons-long processes that formed the Bryce Amphitheater. Rim walks are also offered on a consistent basis and start at Sunset Point. These walks include interesting insights on the geological, biological and cultural history of the area. They last about an hour, and are very accessible, as it's on the paved Rim Trail and just covers a half a mile. Other ad-hoc activities include guided snowshoe hikes (winter only), cultural history walks, astronomy evening programs, stargazing, grand staircase geology talks, bristlecone walks, and more.