This summer, why not try an evening walk at Mission Trails Regional Park? The park, located just across the line in San Diego, encompasses some magnificent scenery, including riparian woods, meadowlands, and much more. Walks begin around dusk, starting at the Kumeyaay Lake Campground entry (just off Mission Gorge Rd. on the west side of Santee), and last about an hour and a half. The walks are free, but the number of people is limited, so you need to call ahead to reserve space.
On walks in previous summers I have seen bats, birds, tarantulas, and a rattlesnake. Well-trained guides lead the walk, explaining the ins and outs of the park and its inhabitants. They will also give you some background on the human history of the area, usually including a stop at some grinding stones. This is a fun way to spend a Saturday evening.