1) Hike up Torrey Pines and walk back along the beach.
2) Ride the roller coaster at Belmont Park – Mission Beach. Check out the overpriced beach/bay for sale properties afterwards.
3) Take the trolley to a Padre game.
4) Explore the many canyons in SD by foot or by bike: Penasquitos, Rose Canyon, San Clemente Canyon, canyons bordering Mission Trails Park in Tierrasanta.
5) Head over to Julian for apple pie (perfect for fall). Check out Lake Cuyamaca along the way.