And Clapton Didn't Even Know

Americana is a broad category and I would include in addition to Little Feat, Los Lobos, Nelville Brothers and The Blasters (Dave Alvin). You could also include the Mothers Of Invention, but that might be a pushing to boundary.

The Band also had a somewhat unique instrumentation. It was far more common at that time period to have two guitar players, but the band instead had twin keyboard players, a pianist and an organist. I can only think of Procol Harum and Mott the Hoople having similar lineups at that time.
Were there others?

Little Feat was a monster. Interesting comparison to The Band - maybe a funkier, muffuletta flavored variation on the same theme. Lowell George was just a hero of mine. From The Mothers to Little Feat, LG spanned just such an amazing range of musical sensibility that I think he might have had one of the great, long careers in popular music had he not died so young. What a shame.

Ditto on the Lowell George hero thing. I luckily saw the classic Feat live a couple
of times, and a couple of post Lowell versions too. Something about George's
gonzo yet precise cerebral soul (from a self described "fat kid from
Hollywood")…I still listen to all the Little Feat stuff and George's solo album
(an amazingly well recorded LP for my tastes anyway) often. There's a new Lowell
George DVD I just read about (Feats First)…interviews and things that looks
really interesting.

The Band was very talented and influential with some good stuff but I tend to prefer classic Little Feat's act more.

Neville Brothers never disappoint.