There is a receiver on its way to Mather, primarily to cover KMHR. All the Sac area NORCAL frequencies are programmed in but locked out for now. 127.4 is already covered on its own feed. Not sure what exact flows/areas are covered by the other Sac frequencies.
125.25 and 134.8 are pretty busy frequencies with aircraft going in and out of KSMF and KSAC. Those would be really cool to hear.
Those are the busiest, yes.. you'll also have 125.4 (covers NE of KSMF), and 123.85 and 124.8 (covers KSCK, but you can hear it clearly from KMHR). With 34.8 covering N/NW, 125.25 covering west, and 23.85 and 24.8 covering south, this gets you full coverage from Beale AFB, KMYV, and KOVE (up to 50nm north of SMF), to KSUU (which should already be covered), to KSCK (40nm south of SMF), to KPVF (30nm east). There we start to lose it in the mountains. But this location would cover the entire Sacramento area.