I-15 Baker to Stateline
You should have D-Fire1-4 and D-Law-1-4 programmed, as they simulcast the 800 Mhz system. You should also program 151.145 for fire simulcast, 154.205 and 154.07 for DesertComm FD, and 154.34 for Clark County Fire. Mercy Air uses 155.22 in Ca, and 453.95 in NV, BLM uses 166.375, and CHP is on 42.56. The 800Mhz system to monitor is System II near Barstow/Victorville, System 3 once you get to Yermo. For the most part, though, the D-Fire/Law-1/2/3/4 channels are the best for the drive. That pretty much covers the Fire/EMS traffic from Barstow to Las Vegas along the I-15. Metro PD (Clark Co. SO) uses 158.85 pL:173.8 in the area.
Also, you should keep in mind the "Tecopa Detour" if travelling from LA to Vegas. It is about 10 miles longer than the direct route, but if there is anything going on on I-15 north of Baker, you will save a lot of time. The detour is as follows:
NB I-15 to the CA-127 Exit.
Exit
Travel North on CA-127 for about 40 miles to Tecopa Hot Springs Road (about 1 mile after entering Inyo County).
Turn Right on Tecopa Hot Springs Road.
Go through town, following the double yellow line.
Continue on this road, now called "Old Spanish Trail" for about 30 minutes
At NV-160, turn Right.
Travel about 30 minutes until you meet back up with I-15 at the Silverton Hotel.
I have used this route many times. There are very few cars on this route, and can save you a lot of time if I-15 is busy.
If you go this way, also program 170.1 for Death Valley NP, 166.375 for BLM Fire, 154.725 for Inyo SO/Tecopa Fire Dispatch, 154.34 and 154.4 for Clark County Fire Dispatch, 154.445 for Pahrump Valley Fire Rescue, and 42.12/42.2 for CHP Bishop Dispatch.