If you have an easy-to-travel-with GPS, I'd bring it along. I noticed that all the folks saying "not necessary" seem to live in that area....yeah, it's easy to get around when you know all the different freeways, lol. And Southern California has several dozen major freeways all criss crossing each other. And mind you, I lived in Southern California for 4 years about 20+ years ago and yet I still prefer to have my GPS with me. It's usually more for reassurance but if you're not familiar with an area, then why not carry a small GPS with you to make life a tad bit easier.
As for your decisions.....while it's definitely possible to drive from Anaheim to San Diego in about 2 hours....remember that for a day trip that means 2 hours returning driving as well. The morning commute up to
Disneyland is an easy one....your fresh and rested, your exicted to get to Disney, etc....the drive home however, your feet and back are aching from hours and hours and hours walking, running, riding and standing at Disneyland. That 2 hours is going to feel like a lot longer....not to mention if you want to get the most out of your day at Disney you are going to want to do rope drop to close, or 8-10 hours....plus 4 hours drive time?
So...I'd try for the extra time to be able to stay near Disney for a short time.
Caveat: Of course, I'm old now...I don't do all nighters anymore, lol. Though back in the day, I can recall more than once getting off work on Friday in San Francisco and a friend and I driving through the night to Disney (about 6 hours or so)...sleeping in the car for a couple hours (back in the days when it was safe to do so, and no one shooed you away)....do Disney all day and drive home again, to crash until time to go to work Monday morning, lol. But, no way now, lol.