Best of both worlds might be an Ultrabook a key-board dockable tablet, like an Asus Transformer Prime or a Surface Pro. But none of these are cheap. In fact, for the cost of some of these you can buy a a good tablet, netbook, AND a decent laptop. If you're only looking to spend a few hundred bucks on a single device though, it all depends on what you're using it for.
Web browsing is easy enough on a tablet. For many sites, like Amazon, eBay, or mobile banking, there'll be an app that is easier to use than the actual website. Most tablets have good enough battery life to play a movie or two while you wait for flights or when you're in the air. And if you're bored in a hotel room, there's plenty of games you can play. If you need to do business stuff, there's apps that do all the .pdf, Excel, Word, etc. But they'll be a bit limited, and not very user friendly.
If you need to do business work, a netbook is probably the better choice. Plus you can connect to USB devices (mouse, external HDD, etc). Some tablets can, some can't. And since they run Windows and have a physical keyboard, it's far easier to do business work on.
BTW, check out an app called PdaNet. It costs $15 (on sale now for $8), but it's a one-time-only cost. It allows you to use your phone's internet connection on your computer via wifi or USB tether, or with your tablet via Blu-Tooth. It depends on your phone, software version, and carrier, but there's usually some way to get it to work. This way you can get internet on your tablet or computer anywhere your phone has data service without paying the outrageous monthly fees your carrier.