The Allman Brothers Band is a great band, here's why:

Great music is defined by attracting cross generational interest, and having a wide applicability for listening.  The Allman Brothers Band fits this.  You'll hear their music in movies of all types, at sporting venues, and on many different types of radio stations (no not just classic rock stations).  You'll even hear it at weddings, and even cooler, Mom and I honored the Allmans by having our Mother/Son dance at my wedding to "Melissa."  Have you heard it?  Here's the song, and pic from that special moment I'll always remember.

Side note, did you know this was the first song they recorded after Duane Allman's death?