I'm going to revive this thread. Ha ha. Just ventured to this forum. Don't remember exactly when, but my longest distance was on my first BMW, a 2002 K1200RS (brick), coming back from a Hill Country rally put together by an old 'i-BMW' forum, and promoted by a 'pirate' guy (a vendor). Did 562 miles, from Kerrville, to El Paso, TX, detouring thru Balmorhea, Ft. Davis, and Kent. The 2nd longest distance was 506 miles, slabbing to that same rally, from El Paso to Kerrville. Other than the awesome twisties of the Davis mountains on the way back, it wasn't pleasant AT ALL. That was the first and last time I did that long of a ride.
On a related note, my longest riding day was on an overnight trip to Alpine, AZ, with tons of super tight twisties in Gila (152,35,15), and Morenci to Alpine (191). About 430 miles, but A TON of hours on the saddle; it was hard work too. I deleted the 35/15 detour on the way back, and on subsequent trips (too many 1st-gear hairpins, which are not my favorite... and 191 has enough).