I"m not saying it is the simplest, but I use MotionX, and it is very good and utterly comprehensive in terms of GPS / Mapping features, so you may want to look into that. See screenie...
I have MotionX GPS HD too.. It's a fantastic GPS app that is capable of showing your real time coordinates and has recently been optimized for geocaching... It's only $2.99 But, it does need 3G to work properly.