Circus Maximus will satisfy all your needs, I like to say "Symphony X" and "Dream Theater" out loud every time a section changes, because most of what they do on the first two albums is alternate between the two + a little Kamelot
"There comes a time when you look into the mirror and you realize that what you see is all that you will ever be. And then you accept it. Or you kill yourself. Or you stop looking in mirrors."
Shadow Gallery was one of the first bands I found after asking this exact same question. They're distinct but they were perfect when the only prog metal bands I had heard were DT and SX.
Wikipedia even says this about Shadow Gallery
"The band has been compared to contemporary progressive metal bands Dream Theater and Symphony X. The members of Shadow Gallery have also collaborated with other progressive metal bands. Dream Theater's James LaBrie contributed backing vocals to the song "I Believe" (which appeared on Shadow Gallery's 1998 album, Tyranny), and in return Shadow Gallery members have contributed to LaBrie's side projects (such as Mullmuzzler)." http://en.wikipedia.org/wiki/Shadow_Gallery
I as well agree with everyone of you. The new DGM album is pretty damn good. I've been listening to that consistently for about a month now, and I enjoy it just as much every time I put it on. I also love the latest two Threshold albums. I've been meaning to check out the rest of their discography as well, but I have the feeling that these last two albums are the most SX and DT influenced. Is that correct?
I can't seem to get into Shadow Gallery though. I don't even know why, because there isn't really anything wrong with their music. Anyone wanna give me some pointers on where to start or something?
You guys should check out Adagio from France. I don't know so much about their earlier albums, but the latest one is really heavy, dark, and riff oriented (at least in a lot of parts). Also, check out Lost In Thought from the UK. They only released one album, and now they've split up. I have no idea why, but that album was really good too, even though this is closer to a DT clone band than for example Adagio.
I guess you can also throw in Anubis Gate and Pagan's Mind. I'm sure you guys know of these two already though...
I sold my soul to any fool who'd buy it!
What's it gonna take to make you riot!?
And you should also check the band Ark, and particulary the album "Burn The Sun". Sometimes, the singer reminds me Russel Allen, which is obviously a good thing I find the atmosphere created by Ark a bit darker than those created by these 2 bands, through the music of course, but also through the lyrics... Anyway, Ark rules !!
Liquid Tension Experiment, Animals as Leaders, Scale the Summit, Iced Earth, James Labrie, John Petrucci, Transatlantic, Flying Colors, Iron Maiden, Testament, Stratovarius, Blotted Science, Pink Floyd, Led Zeppelin, Rush, Mastodon, Joe Satriani, Steve Vai, Derek Sherinian, Jordan Rudess. All of these are very good bands or artists with albums.
Seventh Wonder is a great prog-metal band similar to DT and Symphony X. While I like those bands better, (DT is my fav band), I like Seventh Wonder's singer Tommy Karevik better than Labrie and Allen. Yes, he's that good! Also check out Time Requiem. They also play a similar style, heavy riffs, high pitched clean singing, lots of technically amazing instrumental sections, complex lyrical concepts, etc.