That's great! My first solo trip to Disney World was a result of a business trip too.
Although you have a one-day park hopper, and you probably already know this, you won't be able to do more than just the highlights between the two parks. Each park (especially
Disneyland) is far more dense than Walt Disney World in number of attractions and layout.
Given your short trip and the fact that you're visiting on a Saturday (crowded with locals), I would definitely recommend adding on the MaxPass feature if you haven't already. This will let you use the Disneyland app to reserve FastPass times, giving you an advantage over people who walk to each attraction to get their FastPasses. You have to have entered the park to use MaxPass, so I would go at rope drop and immediately select your first attraction.
Especially toward the end of the night, depending on crowd size, you should be able to get lots of FP selections back to back. The system will tell you when you can get your next FastPass, and unlike WDW, these can overlap with your return window.
I'd check the FP return times before choosing any standby or even single rider lines. Sometimes FP has been faster recently, but not sure if that will change.
If you have any particular questions about Disneyland feel free to ask!