It sounds like you just want to use a Select (on the Programming->Comparisons palette).
Here's an example using a couple of Selects to set motor speeds.
This particular example maintains the last speed chosen by button until overridden by a new button press and it's compatible with the Motor Safety Config if you want to use that:
Using Case statements looks like this (replace the Solenoid Sets with Motor Sets).
This method isn't compatible with the Motor Safety Config:
