When playing TWW, I always treat NV as the 'real' story, and F3 as the looter-shooter funhouse that you visit to try out your cool new grenade launcher in Generic Bandit Ruin #8 or Generic Super Mutant Cave #3 (don't forget the loot chests at the end).
Back in the day, I toyed with the idea of modding the way you switch between the Mojave and Capitol worldspaces. Instead of hopping on the post-apocalyptic transcontinental train (dumb

), there'd be this convoluted setup (autistic

) where you 'go to DC' by sitting down at the bar at the Vikki and Vance Casino and listening to the drunken ramblings of a retired mercenary who claims to have explored DC four years earlier. The gameplay is just you living vicariously through his stories.
"And then we managed to repair the giant robot, but the government goons in power armor were hot on our heels!"
All the flaws of the F3 storyline could then be chalked up to the fact that he's drunk, old, and probably full of ****.