Spreadsheet. First tab (worksheet) is the log itself, details about the trip, mileage, weather, places we went, etc. Cells in 2nd column for the park name or destination are set with a look-up feature to the 2nd tab. When we go back to a place again, it acts as a pick list, keeping spelling consistent. The 2nd tab contains all the details about the park from address to phone numbers, lat/lon coordinates, where we heard about the location, etc. The 3rd tab contains a list of destinations we want to go to in the future. Once we go, to one of the new places, I cut/paste the details into the 2nd tab.
Writing it out, sounds like a lot of work, flows nicely. Much like a relational database, nothing is duplicated!