I've been fulltiming for 2 years now and have used a Verizon MiFi with a Wilson Sleek since I started. I've been all over the western and southern states and I can only recall once or twice where I could not get service.
I can run several devices at once off the MiFi - phone (data), laptop, wireless printer, Tablet, Nook, etc.
You can stick the MiFi in your pocket and head off to the beach or a park if you want to - read a book on your Nook or use your laptop.
I use it for all the things you mentioned.
Campground WiFi is hit and miss. The trouble is that you can't depend on it being 'good' everywhere you go.