In January I came down from from Kingman via Lake Havasu - overnighted in Quartzsite - then onto I-10 into CA and down 78 to El Centro and I-8 into El Cajon. It was a very easy drive - the sand dunes north east of El Centro on that route are very impressive. Towards the upper end of 78 are some 90 degree turns that slow you to 15 or 20 mph. The road surfaces are very good for a CA highway. If it is raining hard 78 can be a problem with water across the road. In that case I'd take I-15 to I-10 to Quaartzsite & US 95 north. Just my opinion.
Bob, Sandi & Marmaduke the Big Pug
SW OREGON 2004 Journey 39K, 330 Cat
If towing: a 2006 Mini Cooper or 1995 Wrangler