I abandoned U2 for a few years in college during which I listened to tons of the Dead.
The Dead went through many eras, mostly based on who came into and left the band. Their earliest line up, featuring Ron "Pigpen" McKernan on keyboards, was the time when they experimented with the blues the most. Pigpen was later replaced by Keith Godchaux, whose wife Donna was a backup singer. This is my favorite era of the band, as I like the harmonies she added to songs like Scarlet Begonias and Fire On the Mountain. They stayed with the band through the late 70s (I think...I'm writing this off the top of my head), and Brett Mydland joined the band as keyboard player in the late 70s and 80s, bringing a much different, almost poppy sound to songs like Far From Me and Touch of Grey.
The Dead's keyboard players, with the exception of Bruce Hornsby (who toured with the band in the 90s but never really officially joined), all met lousy fates. Pigpen died as a result of his alcoholism, Keith Godchaux in a car wreck, and Brett Mydland of a heroin overdose. After Jerry Garcia's death in 1996, the band disbanded for awhile, then tried touring again as the Other Ones, then later as the Dead (where they did a painfully bad version of One).
I've seen Bobby Weir's band Ratdog and Phil Lesh's Phil Lesh and Friends; I didn't much care for Lesh, but I loved Ratdog.
The Dick's Picks series makes it easy to find a quality recording of many Dead shows. I've long lost track of the series, but a few I recommend are volumes 7 and 10, both of which are three-disc sets from the mid 70s. I also recommend the Arista Years compilation for a taste of what they did in the late 70s and early 80s. I can't choose between American Beauty and Workingman's Dead, probably the band's two best-known studio albums, both from the early 70s--both of them have some lousy songs, but each also has some of my favorite Dead songs.
If you don't like long, wandering jams, you'll hate the Grateful Dead. That's why I eventually got bored with them. I love their improvisations, but after awhile, all the 15+ minute drum or guitar solos get a little tiresome
Jeez, I didn't mean to write a novel. Sorry