Here are my suggestions:
Game: Chrono Trigger (SNES) [maybe also using one or more of the extra chips since jaxcheese is doing a 2A03 cover of it]
Playlist: https://www.youtube.com/watch?v=9cFmsMS1QL8Why should the community cover this OST: Because many people like myself regard this as a very memorable and catchy soundtrack, and I think it would translate very well into the NES/Famicom.
Game: Sonic CD (Sega CD) (JP/EU soundtrack since their version sounds way better than the NA tracks)
Playlist: https://www.youtube.com/watch?v=s1iGhVrDQIsWhy should the community cover this OST: Same reason as above. Also, this hasn't been done before, and we have already seen 8-bit renditions of the other Sonic games here on this board, so why not this one too?