The classics have been ported to PC, Gamecube, Wii, Xbox360, PS3.. You don't have to play them on the Genesis. xD
The games after SA2 are kinda ehh, but I'm truly excited for Sonic Generations this November.
I love Sonic Colors! I have it for the Wii.
16-Bit graphics FTW or atleast when it comes to Sonic I love the older games but started to dislike his games after Adventure two, although I do enjoy playing Sonic Colors on my DS