Hmm look at all the NES classics(Metroid, TLOZ, Super Mario Bros(original, secret levels, and 3), There are some okay arcade remakes you could chose from, Wii ware has some Titles and will get more, or you could save it for something thats released in the future.
If you want a challenge, and I mean a hard challenge, get Solomon's Key for the NES. It is an incredibly overlooked puzzle/platformer that will have you screaming at your TV because of the sheer difficulty. Amazing level design, good controls and tons of hidden secrets are what this game is really about.
There's also Kirby's Adventure, an NES game that plays like a current-generation 2-D platformer: It has secret areas that help you unlock more secret areas, a completion percentage, tons of extra features, and text with Masahiro Sakurai's charming wit.