The next remarkable hike is on the Pacific Crest Trail, to Devils Kitchen. However, the walk path is quite tricky, and the final destination is not as impressive as Bumpass Hell. I would recommend it if you have extra days at Lassen Peak.

maps.app.goo.gl/s2sHoKrUGehm...

I highly recommend visiting Cinder Cone volcano near Lassen National Park, which is just a 5-hour drive from San Francisco. You can stay overnight at the nearby campground and hike to the top in morning.

maps.app.goo.gl/UjAn2DcTQY2Q...