For Lenny's Americana stuff I love his 'American in Paris'. ( preferring over his Rhapsody included here )
It's a bit slow compared to other renditions but many beautiful down to earth moments in this performance. Very spirited fresh and Amrican innocence all over. Lacks sophisticated lyrical Euriopean feel and can't help thinking a circus like atmosphere on some spots but love the beefy jazzy gusto. 'Andante' section is gorgeous plus a beautiful finale.
Another very American piece is Grofé's Grand Canyon Suite.
My fave is the Toscanini/NBC version.
Can't get more Americana than the 'On the Trail' but the entire set is very U S of A. Toscanini gives an elegant twist.