Hey Addict, just wanna throw in my two or three cents worth. I went through a seriuos southern rock phase at the age of twenty that lasted about three years. It hasn't completely left me mind you, but sheeeit, I was REALLY into it, totally immersed. My hair was long, I wore a pair of snakeskins, dippin' Copenhagen, not country but country rock. I looked like friggin' Alan Collins man. It was a great time to be into it too because I got to see 'em all in concert: Allmans, Skynard, Hatchett, CDB, Outlaws, ZZ Top, Marshall Tucker, I scooped up the records as fast as I could. So, my qualifications intact, here come my suggestions:
Molly Hatchett - you already mention you have their greatest hits. That's not a bad way to go with these guys. What they did well, they REALLY did well. The rest was, meh. Their first LP is a classic and by far their best. I would think you have just about all their good songs on that one CD, including "Dreams", "Gator Country", and "Bounty Hunter."
If you like them you will like The Outlaws, who like Molly and Skynard, hailed from Florida. "The Guitar Army" featured three lead guitarists and if not for Skynard, these guys would have been much more well known. Their first self-titled LP features the anthemic "Green Grass and High Tides" which is still a classic rock radio staple. Many an air-guitar legend was born when this song came out, including me. Other great songs on this record include "There Goes Another Love Song", another concert favorite, and some other excellent songs that never got airplay. I highly recommend this album. There next one, "Lady in Waiting" has a few concert faves as well: "Why Don't You Stick Around For Some Rock and Roll" is awesome. The band showed some versitility with this release, especially in the beutiful vocal harmonies of "Freeborn Man" and "Breaker Breaker." Their third effort saw some personnel changes. "Hurry Sundown" is another winner, and features a very talented singer/songwriter/bass player named Harvey Dalton Arnold. This record also contains many concert faves; the title track, "So Afraid', "Cold and Lonesome", and "Holiday." This record also continues the tradtion of also containg some very straight forward country songs, which this band was also very good at. Their fouth album was a double live release and samples their first three records pretty well. The sound is good. The band released nine more studio albums but none of them came close to the first three. "Ghost Riders" was released in 1980 and contained a minor hit "Ghost Riders in the Sky." I really liked this song but I don't know the rest of the album. I hoped the hit would restart their career, but it didn't. Oh yeah, Henry Paul was an original member of The Outlaws who left after the second album and formed The Henry Paul Band. His first self-titled LP is very, very good and if you can find it you better get it. It contains a song called "Grey Ghost" which is the best Ronnie Van Zant tribute I have ever heard. An excellent, excellent song that nobody knows about. There are another two or three songs here that are very good also.
Sorry this getting long but I have time for one more band, that'd be The Marshall Tucker Band. I have always loved these guys. More country-ish than the bands from Florida, MTB was from South Carolina and was formed by the Caldwell brothers, Toy on guitar and Tommy on bass. They also feature a little sax and flute on most songs and it fits perfectly. They had some monster hits in the 70's that you might know. "Can't You See" is one of their most famous and is from their first album. "Heard it in a Love Song" was their biggest hit and came on their sixth album, "Carolina Dreams." One of my all time favorite songs "Take the Highway" appears on their first record "The Marshall Tucker Band". I highly suggest you check out the these two albums, along with their third album "Where We All Belong" which is a knockout double LP that's half live and half studio new release. Toy Caldwell was underrated as a guitarist but he had the respect and admiration of his peers. I think some of the guys in Skynard said Toy was the best southern rock guitarist since Duane Allman. Sadly, Toy passed away in the mid 80's, a few years after his brother died tragically. Tucker carries on today on the casino circuit with singer Doug Gray as the only remaining original member, but their catalogue of material stands up to any southern rockers, bar none. No southern rock collection would be anywhere near complete without at least 3 or 4 Tucker albums in it.
Hope this helps.