I think what Lylat meant to say was that they may seem like autoscrollers, as the screen does scroll automatically. But the difference between rail shooters and autoscrollers is that you have the ability to manipulate the speed and the way you advance through a rail shooter, opposed to having 1 strict speed and path through an autoscroller.
Really any game that you personally enjoy, because if you get tired of playing it easily you can't speedrun it. But for a suggestion, Star Fox: Assault is a very fun game to speedrun. It averages about 50 minutes, and it only has 2 glitches that are used in the run. It also has a very supportive and helpful community.
We could just cut out load times to balance Wii & GC times. I vote RTA because it's a lot easier to time, and it makes it easier if you miss the Mission 9 skip.