There's certain games you can't 'beat'. As wel, there's certain games that are either near impossible without codes or just downright frustrating and require hours upon hours of using infinite continues or repetitive dying to find the right way to beat bosses/path/way to get over a ledge (see Angry Video Game Nerd for a good example).
I too am an avid fan of old NES games, but you do have to realize that among the many good games, there were 50 bad ones to back it up. Never has there been a bigger system with more shovelware. The SNES PS2 and DS can never compare.
On your list, the best games I can see are:
Dragon Warrior
A Boy and his Blob
Bubble Bobble (Cannot Beat)
Castlevania (May I suggest finding a copy of Castlevania III)
Double Dragon II
Duck Hunt
Hogans Alley (Cannot beat)
Kirby's Adventure
Ninja Gaiden
Rad Racer
Super Mario Bros 1-3
Teenage Mutant Ninja Turtles II: The Arcade Game
Tetris (Cannot Beat except B-Type)
Legend of Zelda
Legend of Zelda II (though horribly frustrating and takes many continues in its own right)
Six upcoming games you should look into:
