I've done this drive as well, and agree if you take the I-20 freeway out of Dallas and then I-10 all the way to LA, it will not be that interesting.
However, depending on your time for detours, it can be fun.
From Texas through New Mexico it will suck, no way around it. Once you get into Arizona, you could detour north to Sedona (beautiful red rock formations and scenery and hiking there) and then take the I-40 from Flagstaff (just north of Sedona) heading west out of Arizona back into California, which goes through some nice mountain passes with sweeping curves (you have to maintain seriously illegal speeds to make these curves into proper corners). I really enjoyed that drive on another trip I took.
The I-40 from Arizona also passes through Lake Havasu, which is a popular destination, and then meets the I-15 in Barstow, California where the fun ends and you can take the rest of the drive into LA from the north-east.
If you have time for that it might be worth it, but the fact that you have to drive from Dallas to Phoenix before it gets interesting means that 75% of the driving will still be boring (mostly flat and straight) interstate freeways.
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