IGN let slip the entire setlist for GH: Smash Hits.  The wiki article lists them all, but here are the new ones from GH80s and a surprise inclusion from GH:A.

Guitar Hero Encore: Rocks the 80s

* Anthrax - "Caught In A Mosh"
* Extreme - "Play With Me"
* Judas Priest - "Electric Eye"
* Poison - "Nothin' But A Good Time"
* Ratt - "Round and Round"
* Twisted Sister - "I Wanna Rock"

Guitar Hero: Aerosmith

* Aerosmith - "Back In The Saddle"

These seem like good tracks to choose from GH80s, overall, but there's one glaring ommission: New Wave.  These are all metal and glam metal tracks.  They should have gone with Only A Lad, I Ran (So Far Away), or Turning Japanese at the very least.

Cool, I guess, that an Aerosmith track made it in, but whatever.  I would rather have had the original version of Walk This Way.

They're missing flock of seagulls - best song on RT80s, and possibly every guitar hero game.

I Ran, Turning Japanese and Seventeen are the biggest omissions I see from that list. Shame, all of those would've been a blast, especially on vocals. Only a Lad would've been great too, since it was one of my favorites from that game. Oh well.

Play With Me is going to be epic. Same with Caught in the Mosh.

Aww, dang it I was hoping if an Aerosmith song made it, King of Rock would of been on there.  Vocals ftw!

Also sucks that Hangar 18, Jordan, Paint It Black, Misirlou, and Institutionalized didn't make it on there.  Hope Rock Band can get Rust in Peace at least.

I have absolutely no understanding for the exclusion of Guns'n'Roses - Sweet Child of Mine. How does that awesome hit not make the cut?!

That's just terribly sad and I'd wish Axl would grow to realize that Guns N' Roses was and not is.