One of my favorite things about the Wii was that it made arcade-style rail shooters relevant to home console gaming. No requirement to buy a bulky plastic gun (but you can get that sweet Nyko shell if you like), and no calibration necessary. No needing to navigate menus with one controller and shooting with the plastic light gun. They're the simple pick-up-and-play games they were meant to be.
Freed to the build depth into them, though, some developers were very crafty with their rail shooters. As such, I recommend the following in order of quality from best to worst:
House of the Dead: Overkill
Dead Space Extraction (Excellent if you're a Dead Space fan as this adds to the overall narrative of the franchise)
Resident Evil Umbrella Chronicles (not perfect, but a solid game with great, though sometimes silly challenges and modes)
Resident Evil Darkside Chronicles (this improved a lot of things over UC, but featured a "realism shaky camera" that hindered some of the gameplay)
House of the Dead 2 & 3 Return (good classic arcade shooter action, eventually with unlimited continues)
Resist the urge to be a dumbass and dismiss the games as "just rail shooters" as rail shooters are actually pretty fun, and these especially are.
I would also recommend:
MadWorld
Kirby's Epic Yarn
Punch-Out!! (remake)
World of Goo (WiiWare)
Contra ReBirth (WiiWare)
No More Heroes 1 & 2
Manhunt 2--imperfect in many ways, but the motion controls seriously add a lot to the game.
Muramasa: Demon Blade
...some others. I may get back to you, but I'm trying to give you something different from some of the obvious titles other gamers will suggest.
