If you use your bike+ car option this is irrelevant, but starting from fair oaks I’d rather work my way over to monument drive, government center parkway, jermantown road, chain bridge, courthouse, plum, elm, cherry, w&od. The other way I prefer tapawingo through the park to oleander, brightlea, edgelea, to blake/jermantown. (because the courthouse/chain bridge intersection is a death trap west bound.) That’s a lot more turns, but less out of the way than lawyer’s, flatter, and more quiet street on-road possibilities. (The streets being much faster than the side paths.) I agree that you probably want to start with less than 30 miles one-way. The first day with a heavy afternoon headwind would suck.