The closest range to Monrovia is probably Fish Canyon, but it's a pain. They prohibit just about everything, it costs more, you have to use their targets (no targets besides paper--not even fruits and veggies!) and they have ragged rifle tables that will give you 4" splinters.
San Gabriel Valley Gun Range (or Fish Canyon, as regulars like to call it, since it's on Fish Canyon Rd.), is not nearly that bad. No, you can't shoot fruits or veggies, but you can bring steel spinners (minimum 50 yds.). Otherwise, it's paper targets at 50 ft., 25 yds., 50 yds., 100 yds., or 200 yds. No steel ammo (fire hazard for most CA ranges, IINM) and no rapid firing (one shot every two seconds), that's about it. All day admission is, IIRC, $9 on weekdays, $10 on weekends. It's probably +/- $1 compared to other ranges. About half their tables have been replaced with new tabletops (no splinters). Fish Canyon is my favorite range to shoot at. The somewhat stricter adherence to rules makes me feel safer than when I'm at Burro (where pretty much anything goes).
At Burro, I've seen guys go full auto at a bowling pin two yards away (and miss every shot, of course). They think it's fun/funny, I think it's dangerous. No steel ammo at Burro, either. No shade, rickety benches and lawn chairs suck, no clearly marked lanes (lots of crossfire at your targets) with clearly marked distances. But you can shoot fruits, veggies, clay pigeons, bowling pins, golf balls, etc, whether they're yours or not. Restrooms are portable.
Angeles is even more stringent with steel ammo, and they WILL kick you off the range if you're caught (Fish Canyon will give you at least one warning). No fruits or veggies here, either. Only paper or steel. Workers there, not very friendly to begin with, enforce their rules with glee. If you're shooting rifles, their rifle section is nice (although WINDY). Concrete benches w/ metal folding chairs. You can shoot at steel silhouettes up to 600 yds. away. The pistol section has rows of steel spinners set up at 35, 50, and 100 yds. away. Those are fun. You HAVE to sweep up your brass, though, or they'll hold up line break for everyone til you do.
Every range has its pros/cons. I go to Fish Canyon every weekend. It's closest, and the people there are friendly. And they have a burger joint if you're hungry. Hope that helps.