Puddles said:
I'm an entry-level metal guy. I have pretty much everything by Metallica, Maiden and Sabbath, as well as a few other essentials (Reign in Blood, Rust in Peace, Nightfall in Middle Earth, Deliverance).
Given that I'm not a huge fan of bands that only do the growl/demon style vocals (but I can deal with it if it's mixed in with normal vocals and good melodies, like with Opeth), and that I really like the massive guitar riffs and melodic leads of Metallica/Maiden, where should I go from here?
If you dig Opeth, odds are you'll appreciate Edge of Sanity. They're another progressive death metal type band from the same scene. Check out Crimson 1 and 2 and Purgatory Afterglow (Crimson features Åkerfeldt on guest vocals). They're mostly growled but Swano does some clean vocals too.
Also, Katatonia's releases with Åkerfeldt on vocals are amazing. Brave Murder Day and Sounds of Decay are essential. The first has some songs with clean vocals (not by Åkerfeldt though). But if you're anything like me, you'll be used to his growls after a little while. Might as well continue with something you're familiar with.
If you want more Maiden-esque stuff, you should definitely check out Bruce Dickinsons solo career, especially the last three albums. It's essentially a slightly heavier version of Iron Maiden. Accident of Birth and Chemical Wedding (the best one) both feature Adrian Smith from Maiden on guitar so there's the riffs have a very familiar feeling, but veer slightly more towards the heavy compared to Maidens harmonics. I've mentioned it before in this thread, but Bruce's solo stuff is really underrated.
Finally, keep listening to growling stuff, you'll get used to it eventually.
You might also want to check out the whole Sludge scene, bands like Isis usually get crossover fans who aren't really metal-people, despite using harsh (and clean) vocals.