I have this exact problem even without the travel... A couple of days at home without continuous jobs / tasks needing to get done. Great, I can finally get onto doing some work for project X!
Except it never happens. Seems my motivation / drive is so depleted that the best way to use the days off is to actually rest. Then I feel great (although generally a little miffed that I didn't get anything done on project X) and for the next several weeks I seem to have more focus and be able to get my everyday things done more effectively.
Sometimes the best way to utilise a break is exactly that - have a (complete) break and just rest the mind - I find some physical exercise (surfing) helpful with that too.
Yes we often sticked to the nine to five work template, doing the fun stuff in weekends and vacations. And off course, when you take the moped after work to go and see that sunset, that's also heaven for a few hours :)
Again GTD is a good way to make your way through work.
Also: when you're on the road, you won't need to go and see family and friends. You'll miss them. But a lot of time is free to do other stuff.
Though as far as i understood, they solved this with going out as tourists only on weekends.