The Crystal Palace is closed Mondays, but has live music pretty much every other night of the week. Sometimes on the weekends they have concerts for an extra fee, so check their schedule to see if you'll need tickets. They are going to be the most "showy" place, and a unique venue if you are country music fan. The place is like a mini museum for Buck Owens. It's worth checking out. http://www.buckowens.com/concerts.html
Trouts is a legend in Bakersfield. Nothing fancy like Buck Owens, but it's been around forever. The crowds change over the years, sometimes it's a bit of a scary place. I haven't been there in years so I can't tell you what it's looking like these days, but they generally have live music. It's definitely an experience!
Ethel's Old Corral is also a fun little place. You can tie up your horses out front. :) I think they have live music on the weekends. You can find them on Facebook for more info.
You'll be here the last weekend of our county fair. All concerts are free with fair admission, and there might be something there you like. I haven't seen the entertainment lineup yet, but google the kern county fair website for more info.
Those are some of highlights, but you should have plenty of options in town, especially Saturday. Have fun!