I put VMS on the Ipad and is compatible to Iphone and some Ipods, it's good because you can use the different size screens etc for different things. Iphone /Ipod if you only want to use a small screen on road gps (doesn't stop you with the Ipad either) and then the Ipad for bigger view of the area you are wheeling in which is what I have done.

I always have paper maps with me as well.