Excellent advice -- and sorry, I tried to post a somewhat lengthy reply which took into consideration what you guys wrote. But it got eaten up by Fodor's twice when I tried to upload.
So just these few lines to let you know that I appreciate all your brains, and that I've been reading all replies.
I'll try again to post some explanations re. Vegas and LA after this.. hopefully it will work out this time.

Sorry you are having problems with losing a long post. I have noticed that down in the lower right corner of the box, there is a "yellow auto save" that shows up a few seconds after you stop typing.
If you do fly to SFO (or Oakland), you can take the Amtrak Coast Starlight south to Santa Barbara (6 PM arrival). Rent a car there to visit southern California and perhaps Las Vegas.

Las Vegas, aside from PaulRabe's great words "has to be seen to be disbelieved" is also a great gateway to the national or state parks of Utah and Arizona. Other major airports like SLC or Phoenix or Denver are just not as centrally located if you want to do a wide or narrow loop trip around the Grand Canyon.

Los Angeles, not that I would not like it - it's just not my favorite destination in the West where I would usually lean towards visiting just one more national park than spending time in that mega city. So only a personal preference between town and country.

@Nelson.. Monument Valley still is, mass tourism effects acknowledged, one of my favorite sites.. I've seen more than one Western flick filmed on location there. And I must have driven that dirt loop road 10+ times. I think it's one of those few places that you have seen a zillion times in films and on posters or calenders and in coffee table books, but when you actually get there.. it's still and over and over again a big WOW.

I might opt for NYC, Washington DC, and Miami (or New Orleans).

If you want the cool accommodations in any national park, book asap. :) I believe they allow booking 1 year in advance.