Good replies all! Thanks.
I am crossing Nv down there to get to Ca near Yosemite and from there to head north.
I kind want to say I've been around Area 51. I will carry about 1.5 gallons of gas with me, but all the advice re winds and mileage and paucity of stations is well-taken. !2mi to Alamo is probably a worthwhile detour. !90 miles is close to the limit of my tank when completely full, esp if headwinds and speed.
I thought Cathedral Gorge looked interesting and that's what drew me to crossing via Cedar City--or from St George up 18 the across-- rather than 15 down to 168.
I am going to be on a BMW roadster--600+# loaded-- so I really prefer pavement, but some hard packed graded mud/gravel is ok in a pinch. Point is, the area is of interest to me, but there is a lot farther to travel on this ride. Lots farther. There will not be a lot of time for exploring in this area.
So, to distill my question down a little more: which is the neater ride? The Caliente route or the Mesquite route in your view?
Thanks again, excellent help.