Road trip from San Diego to Austin
That's a really long drive, and it seems even longer than it actually is coming east, because you lose two hours. And believe me, I know, because I've driven it many times, most recently, just a few months ago.
There's a lot of good food and stuff to see and do on the San Diego to El Paso portion, but then there's basically nothing from El Paso until you get closer to Fredericksburg and the Texas Hill Country. In fact, after many attempts to find a decent meal on that portion of the drive, I've basically given up, and just pack a cooler.
If you're trying to do it all in two days, you're not going to have much time to "stop and gorge." I'd seriously suggest you break it into three. At least try to leave San Diego and get to Yuma day 1. Obviously I don't know your time constraints or schedule but, assuming you have a day job of some sort, I'd advise you to leave work and just get a few hours under your belt, at least three or four. If all you do is make it to Yuma, there is good Mexican food there. http://chowhound.chow.com/topics/9708... You could hit one of those spots for dinner and then get a fine Mexican breakfast the next morning.
You also go through Phoenix and Tucson, both of which have a lot of good stop-and-gorge-worthy options. And then you'll make it to the Las Cruces/Mesilla/Hatch/El Paso area, where there is also a lot of really great food to choose from. Stop for the night there.
And then, do as I do, and load up a cooler for that long, smooth cruise across West Texas.
The best thing about it is that you'll make great time.
Agree with Jaymes on nothing between EP and the hill country....if you're staying on IH-10.
If you're willing to detour for a overnight in Marfa (home of the "lights" and a fabulous minimalist art museum), don't miss Cochineal, a culinary oasis if there ever was one.