Actually, the newest version of Google maps does allow for pre-caching of maps. It is described in the link below. You can then use Google maps on your phone without cellular signal, no problem. You can cache multiple areas.
1. In Google Maps on your phone, "Use the search box at the top to find the location whose map you want to save for offline use. Alternatively, you can navigate to the area manually that you want to save for offline use.
2. Now, type “ok maps” in the search box at the top and Google Maps will pre-cache the Map area being shown on-screen for offline use.
Read more at
http://www.cultofandroid.com/34026/save-maps-for-offline-use-in-the-new-google-maps-for-android/#b1fDiZvqCJlRgvKF.99
I am on a Droid and Airplane mode is good, but turning off the "Radio" is better. I will look into those GPS programs as currently I only have Google Maps and they don't allow you to download the maps in advance or load a GPX file.