almost ALL of the bands posted are mainstream. In a topic like this, that's rather dumb to do, since everyone's already heard of pink floyd and the red hot chili peppers. No offense to those bands or the people who like them, I think they're pretty good too. I think in a topic like this you should describe bands people DON'T already hear all the time
I've got a lot of bands I could recommend here for various reasons, but I'm gonna devote this post to Disillusion. If you're a fan of bands such as Opeth, or any other band that mixes musical styles you will love this band. Note that the band has some harsh vocals, so you will have to have an ear for those. They currently only have one album; Back to Times of Splendor, but its an amazing one. I recommend basically the whole album, as personally I think it sounds best from end to end. Many people disagree with me, however, so the best songs to get into them are probably the title track, (pretty long but its amazing, and delves into more than one of their sounds) and The Sleep of Restless Hours. (Even longer, 17 minutes... but its just... amazing. You have to hear it to understand.) A lot of people also like the shortest song on the album; Fall. It's also a pretty good one. This is my favorite album of all time, and I recommend it to anyone who can stand metal with some harsh vocals (though it has non-harsh ones that are extremely catchy too)
Two songs from the album; Fall and And the Mirror Cracked (the first song on the album) can be found on the band's myspace. If it doesn't agree with you at first give it a chance, you may find it grows on you as it changes genres.
Disillusion's MyspaceI might do another one for another band I like later, but this is it for now; enjoy
Oh, and Children of Bodom are (at least I believe) Power metal with harsh vocals, though I'll put some of their stuff in the realm of Melodic Death Metal. NOTHING they ever wrote is melodic black metal, however. I could introduce you to a few melodic black bands if you'd like, its good stuff if you have an ear for it.