Have driven the other direction - from Los Angeles to Custer, SD for the annual Sound of Silence (Black Hills Tesla Rally) festivities in late May. Itself worth searching for in this forum or at the TM forum for more info. It's a must-do trip and about as much fun as can be packed into a weekend. Plus it's a SC-all-the-way trip, and Custer has 48 chargers during the event. Most connected small town on the continent.
So if you map the above journey using evtripplanner, you'll see the SCs through NV, AZ and Utah, plus the 2 in Cheyenne and Lusk. Note the Cheyenne chargers are hidden amongst a sea of RVs most of the year, and there's a puddle around 2 of the spaces, so watch where you step. The Lusk charger is located at a very nice motel for the area, and the food is surprisingly good not at the adjacent drive-in but diagonally up the block at a local diner - with about a dozen different kinds of pies. But I digress, as you probably won't need either of those chargers unless you do decide to attend the rally next month or one of these years.
So for the Vegas trip, be sure to download and review the .csv file from evtripplanner as it will show those legs with more or less net elevation. For example, the stretch east from Green River, Utah (despite leaving with considerably more than the recommended charge) caused Nav/Trip Planner to have a hissy fit and resulted in making a long day even longer due to an unnecessary return for additional charging (I had 74%, and returned for 95%). In that case, there was a bug, since confirmed and presumably fixed, but the point is that by knowing what legs may or may have elevation concerns, you can add charging sufficient to reduce any concerns or wasted time.
I plan to loop through OR WA ID MT on the way to Yellowstone (WY) in a couple of months, but haven't mapped the route. I've been told to allow at least 3 days for Yellowstone itself, and will rely upon Plugshare for any destination charging that might be necessary.
One recommendation I would make, although you probably won't need it, is to buy or to borrow a ChaDeMo adapter if Plugshare shows a few along the way (look for the orange icons and configure to taste in the settings). Some regional networks are excellent (see AeroVironment's full-strength, fully-functional ChaDeMo network along the coast of Oregon), and some are all but useless - however, most Nissan dealerships will have at least a throttled (by manufacture) 20kW ChaDeMo that may or may not be available during business hours. I've experienced very kind accommodation at the dealership in Tucson, for example, but have heard tales of exactly the converse elsewhere. In any case, ChaDeMo chargers are the only game in town other than SCs for making way as one might with an ICE.
Destination chargers are only useful for overnights or, of course, places you choose to visit where there is just nothing else around and you need enough to get to the nearest SC.