Gautham,
Congrats on the Atlantis and a great build! With 2.1s and fenders it's ready for anything.
Tyler,
My only Rivendell is a Platypus, which
Riv says is "like an Appaloosa or Atlantis, but with a step through frame", and it's the longest (single seat) bike I own. My 60cm Platy is also sized up to a larger size than I could stand over on an Atlantis, so I'm taking the long wheelbase thing and running with it.
I might not call the Platypus "playful" in the same way I would some of my other bikes, but neither the functionality nor the fun factor are compromised by the bike's wheelbase.
I like to describe the ride as "cruisy zoomy" - it's easy going and zippy, but at the same time is plenty maneuverable. I've managed some surprisingly tight turns on single track, have been able to lift the front wheel over obstacles, and can lift the rear wheel off the ground without much more effort than my shorter bikes (not hopping, just weight shifting).
-Dave