Well, as a member of the 30something crowd, I can say a lot of my formative years with D&D-esque materials were:
- Reading the Lloyd Alexander books after The Black Cauldron came out in theaters (IIRC, I was in elementary school at the time).
- Seeing movies like Bakshi's The Lord of the Rings, the Rankin-Bass The Hobbit, Conan the Barbarian, Excalibur, Dragonslayer, and the Disney Robin Hood and The Sword in the Stone (and, FWIW, the 'original' Star Wars trilogy).
- Cartoons like Masters of the Universe, Thundercats, and Dungeons & Dragons.
Around the end of middle school/start of junior high, I really got into D&D and computer games with a fantasy theme (Ultima, Might & Magic, Zork, the Gold Box games, etc.). I read the Dragonlance Chronicles & Legends then, followed by a successful read of The Hobbit and LOTR (tried many times when I was younger, but couldn't get into it). Read a fair amount of the D&D-based fiction, as well as Asprin's Myth Adventures series.
(FYI: I got into D&D around the end of 1st ed./rise of 2nd ed., and the reign of BECMI D&D.)
However, it wasn't until college that I got into Leiber, Howard, Moorcock, Vance, and other "formative" authors for D&D. I only did thanks to the "recommended reading" lists present in 1st ed./BECMI copies of the games.
My big D&D days of my "prime" happened to be during the days when Magic first took off, and the Storyteller system took hold (the days of the trend of trenchcoats & katanas, if you will); essentially back when FR was the uber-cool setting for D&D, but D&D was seen as gauche in some gaming circles, and not too trendy by some.