You going to Palm Springs or Joshua Tree NP while you’re in LA area? Pappy & Harriets is a great biker bar near 29 Palms (which is also kind of a funky town to check out). Also, riding across Death Valley this time of year is good. Check roads before you go to make sure you know what’s open. They had some flood closures but I think a lot is back open again. Panamint Springs has a funky hotel you can stay at with hot springs nearby. Furnace Creek Ranch is more spendy but nice. And the Inn there is top notch but pricey. Otherwise you can stay in Beatty in NV on the other side of DV.
Re Grand Canyon, from LV you can head North East up through Zion and Bryce Canyon, then loop around and catch the North Rim of the Grand Canyon (much less visited), then turn it into a big loop and work your way back down to the South Rim via Moab and Canyonlands NP.
Lots to see there. If you plan on hitting more than a couple of national parks you may want to consider buying a national park annual pass for USD80 - less expensive than paying entry fees if you visit several parks.
Love that part of the country and have toured a lot of it. Enjoy!