I use Navigon and if it cannot get a gps link it will show you a simulated route. I love this app - paid $60 for it and was able to load on both my ipad and iphone so have a GPS on both for one price. When I am the navigator on a trip I use the ipad and have a nice big map.
Is there an ap that allows you to cache/save multiple destinations in the native Ipad2 Map program? I know it allows one destination to be cached where you do not need wifi. It would be very handy to have IMO and I already have nav in my car.