Right, so you've knocked out enough songs in I and II to get the complete set list (not including the lame-o extra songs), and you're saying something like "Why isn't _______ in here?"
Well, I was. Maybe you weren't. But this is my blog, so we'll go with my idea.
What songs ought to be in Guitar Hero III? Yes, there are a million posts on this already, but I don't feel like being original, and anyway, I don't care what anyone else wants.
Dire Straits - Money for Nothing
Doobie Brothers - China Grove
Any Zeppelin song
Dueling Banjos. Don't tell me this wouldn't be an awesome two-player song.
Queen - Bohemian Rhapsody. Has the added benefit of causing involuntary headbanging in 90% of observed instances of play. An automatic two-player win for you if you can resist.
Guns N Roses - Welcome to the Jungle. You got the slow song in, now give us a harder one.
Aerosmith - Walk This Way. Same thing. By the way, please don't ever use that guy's voice for Steven Tyler again. He's not even close.
Cheap Trick - Don't Be Cruel. Bonus points for it being an Elvis cover. I have no idea how well they'd do the walking bass line, but it would sure be worth it.
How about some Freedom Rock selections?
Jethro Tull - Locomotive Breath.
Derek and the Dominos - Layla. (If you don't get a special feeling any time you try to play Clapton, this is not the game for you.)
Allman Brothers - Ramblin' Man.
This is still a work in progress. Links and stuff to come. I bet I can come up with a list of 40 songs (8x5 like GH II, no, not like the color glossy pictures with circles and arrows and a paragraph on the back of each one).
Whitesnake - Still of the Night. I'd never be able to play it on Expert, but I'd love to watch someone else do it. (I vaguely recall trying to play the bass line.)
Kiss - Detroit Rock City. Don't question me.
Ted Nugent - Cat Scratch Fever. An air-guitar standard.
Peter Frampton - Show Me the Way. Bonus points if we get a wah-wah pedal for the 360.
Charlie Daniels Band - The Devil Went Down to Georgia. Now that might be a 7th- or 8th-set song.
Eagles - Hotel California.
Eric Johnson - Cliffs of Dover. Presumably, this would be in one of the last two sets.
Cars - My Best Friend's Girl. This would be kind of like the Stray Cats tune: not flashy, but a good technical challenge.