You can move files from your Mac laptop to the iPad turning on iTunes, plugging the iPad into the Mac with its charging cord, and synching.
My iPad2 is a 32GB wi-fi only. It holds TONS of stuff. I use Files Pro to store my files on the iPad. It is especially important to consider whether you will have access to the cloud or live internet. Since I don't, my app choices may not be the same as yours. Do a search on some of the recent iPad threads on RV.net to see what others use.
I even rented a movie from iTunes to take on my next trip; it took almost 2 hours to download that movie, so it must be a huge file. It went onto the iPad in a second or two during the synch.
Thanks for the hint on the Benchmark atlas apps. I'll check those out before my planned Oregon trip this summer.
And speaking of checking out, you can often check out e-books from your home library for free to read offline later on your iThing.