There are five candidates for SD-7, Democrat Mark DeSaulnier's district include assemblywoman Susan Bonilla, former assemblywoman Joan Buchanan, and 2014 assembly candidate Steve Glazer. All are Democrats and all should raise a decent amount of money. Michaela Hertle is the lone Republican. The Republican got 43% of the primary vote in 2012. So Hertle is likely to finish first and lose to which ever Democrat finishes second.
SD-21 was vacated when Republican Steve Knight resigned to take the CA-25 congressional seat. Republican Sharon Runner was the lone candidate to file. She occupied a similar state senate seat from 2009 to 2011, but resigned due to health reasons. I believe she can serve the remainder of this term and one additional term before being termed out. This is only a state senate special election but Democrats' inability to find a candidate doesn't bode well for their chances of having one that can beat Knight in 2016. I remain convinced they'll try to get Fran Pavley to run. She's a state senator from a neighboring district but could move here to run for congress. Democrats did something similar in 2012 for the Ventura county based CA-26. Julia Brownley was from Santa Monica and is now in congress. A carpetbagging candidate is likely their only hope.
SD-37 was vacated when Republican Mimi Walters resigned to take the CA-45 congressional seat. No Democrat filed here but assemblyman Don Wagner, former Supervisor John Moorlach, and Dana Rohrabacher campaign staffer Naz Namazi, all Republicans, filed. I'm sure your first thought is why does Dana Rohrabacher have a campaign staffer? I can't answer that but his presence should deny Moorlach and Wagner, the stronger candidates, a first round victory. This one will go to a run-off.