I'd recommend this if you can contact the author and ask for a stripped down version (e.g. no intro, no intermission, the actual song is cool). edit: oh and yeah, those screens look awesome, positivefeedback++
I still think Teezord's Emerald Hill one is the only song in this entire lineup of suggestions that actually sounds like it'd fit in the background of a Sonic level.
Holy shit! Call this fangame Sonic Dream. Well, because we dream when we see the images :3 [/joke] Srsly. Awesome work.
I'm going to jump on the band-wagon and suggest this: http://www.youtube.com/watch?v=VsNmOV2oP-4 I know, it's used in Sonic XG and it's really the Marvel vs Capcom 1 Credits music, but if someone could do a tropical samba remix of it, it could suit this game also in my opinion
My problem is that I've never heard a GHZ remix I've liked. It's gonna be tough to find anything suitable.
I don't know if it would fit the game 100%, but why not try some Battle Garegga music? http://www.youtube.com/watch?v=3iEvJfdemUs (youtube tag didn't work)
So far the only good GHZ remix in here is the OneUp Studios one, and as a bonus it actually fits the evening setting. Perhaps you would be better picking a different song, one of the Palmtree Panic ones or something.