Realizing you may not always have access to wi-fi (or a good 3G data signal) I would recommend the HP Play program for your home computer and a selection of songs and playlists that you want with you at all times.
A good weather app (Weatherbug for free will do the trick, haven't tried Weather Dashboard, but it sounds like it's worth the money)
Look to see if the airports you will be at have free wifi, it's always better than tethering.
Angry Birds, Angry Birds Rio, QuickSudoko are my game mainstays
Headphones to keep your noise to yourself when you need it is critical
The news apps of your choice, whether that be USA Today (a beautiful app), LA Times or NY Times Reader, etc.
If you can convert a movie or two to mp4 format, you will not have to rely on the HP Movie Store, but that will be a good option if you have a steady wifi at your destination (I wouldn't try streaming that over 3G)
Keep your charger handy for plugging in at airports, coffee shops, etc.
I spent two weeks out of July traveling, and the Touchpad was my main form of entertainment and at some times communication. A skype account with Google Voice can replace your phone if you find yourself out of cellular coverage but have wifi access.
Enjoy. This is the perfect device for away from home access.