The paved fire road up to the top of Cuyamaca Peak from the Paso Picacho campground also has some killer steep sections, as well as a killer view from the top. It's maybe a 500'/mile climb overall, from 4900' to 6500', and while closed to cars, is open to bikes.
Dictionary Hill, east of San Diego proper, also has many very steep streets. Seems it was laid out in a grid pattern on a map regardless of the terrain, maybe to fool buyers that bought a lot unseen.