I just got back from a couple of days on the road for work myself. You are right that it's a good idea to have a plan in place for any trip. Think of it this way maybe - you will very likely have a very detailed agenda for the work that you will be doing while gone, right? Then there's no reason you can't do the same for the time that you will not be working.
Think of all the new and exiciting things that there are to do in see when you are in a new place, or even a place that you have been but don't go to often. Museums, art galleries, historical sites, shopping, local natural areas, you name it. I enjoy guitars and playing them, so one of the things I always look for before I leave is a list of local guitar and/or pawn shops to go check out. You can research just about any of the places I mentioned above on the internet and find reviews.
It doesn't need to be complicated - instead of thinking about what you USED to do when you were on a buisiness trip - thing of what you are GOING to do differently instead. And write it down like an itinerary if you have to - become your own personal tour guide!