Whether your literary tastes run to _On the Road_, _Travels with Charley_, or _Wild_, you'll enjoy seeing these epic trips mapped out.

I love Atlas Obscura - they have some neat gems in the Bay Area you can visit too. :) 

Wow, Rose, they have a lot:

http://atlasobscura.com/search?utf8=✓&lat=37.7746980044634&lng=-122.41719&q=&formatted_address=San+Francisco

Any you recommend?

I like the V.C. Morris Gift Shop - but I had no idea people call it that. It's the Xanadu Gallery, and I was lucky enough to get shown around basement when I was there. They had tons of stuff that was not yet on display such as funerary art, an early form of Ethiopian currency, etc. You can even see the hinge for the entrance door - it makes this really loud creaking noise that you only hear in the basement. Never seen that anywhere else before...   

Rose, neat! It has the touch of Frank Lloyd Wright:

http://atlasobscura.com/places/v-c-morris-gift-shop

Thank you for the recommendation!

Yes it does - of course!

I never realized Mark Twain visited Hawaii!

Roughing It, Mark Twain. 1872. Twain's book about his journey west by stagecoach a decade earlier is a incredible account of transcontinental travel before the railroad made it infinitely easier; his sections about the early Mormons in Salt Lake City, the mining settlements in Nevada and the pre-Americanized Sandwich Islands--aka, Hawaii--are also well worth the read. 

Makes me wonder what turns a road trip epic?

Is it the adventures? The distance? The time? Some combination?