Well,......this is a funny thread! OP says "LA" which could be the state, or did he mean L.A.? He says I-10 West (which excludes Louisiana), so lets assume it's Los Angeles (although he says his "first long trip", and PHX to L.A. is hardly a "long" trip,.....confusing......
Since I live in both states (AZ, and CA) and have homes in both, I drive I-10 East and West VERY often. I drove I-10 East recently (early January), all the way to mid TX, and all the way to Tallahassee, FL in the past. One can say I know I-10 from Santa Monica to Tallahassee pretty well.
One of my residencies is 5 miles north of I-10 in the San Gorgonio Pass in CA (at 3000' elevation), and I can see I-10 down below from my deck.
IF traveling EAST to Louisiana, be VERY careful of NM speed traps! They put a white (unmarked) pickup in the median, and clock you just few miles from the State Line. A mile or so after the pickup, they have six-seven squad cars, and pull EVERYBODY over! It looks like a parking lot (with high fees). Scenery in NM is nice though. Driving through TX is boring as hell (as mentioned above).
IF traveling WEST to Los Angeles, the road is good and pavement almost new from Tonopah to CA State Line. Past Quartzsite scenery is pretty to the river (20 miles or so), otherwise boring. A mile from the river (on CA side) is agricultural inspection (with Border Patrol, and CHP in attendance most of the time). Out of Blythe there is a slight grade up to the prisons (on your left), and right there they have speed traps ALL THE TIME. Be careful. From the prisons to Chiriaco Summit it's mostly flat, with a slight grade 5-6 miles before the summit. Then it's downhill to Coachella Valley (CHP waiting on the downhill occasionally). Desert floor is flat off course, with lot of traffic through the desert cities.
Past Palm Springs and HWY 62, there is a Whitewater grade (pretty steep) with lots of trucks (scales are just on the other side). Downhill from Whitewater to Cabazon is very gradual,....no big deal. Past Cabazon you have couple of small grades (one in Banning, and one in from Calimesa to Yucaipa), but after Redlands, it's all flat to Santa Monica.
Hope this helps.