Since a wireless Internet connection (wifi) is required for a tablet, a smart phone may be your best bet when you are away from home.
If you shop for a tablet and are not used to Apple products, you will find there are lots of Android tablets available that you can use without having to learn Apple's way of doing things. We have a Toshiba Thrive -- an Android tablet similar to an iPad. Unlike an iPad, however, it has HDMI and USB ports and another little port (don't know what it is called.)
It (and the iPad too, I assume) also functions as an e-reader just by downloading the Kindle app.
Be sure to research everything before you put your money down. There are lots of sites that review this kind of technology. You can google "tablet computer reviews" or something similar. Same for phones.
Best of luck in your search.