I just ran out of space on my phone. So, I deleted a bunch of apps that seemed like a good idea at the time, but I have never used.
There are probably a gazillion travel apps out there, but very few are worthwhile. One of them is a map and navigation app called Navmii. The great thing about it is that you don’t have to have a data connection to use it. You simply download the maps that you want to use. If you’re planning an international trip, just download that country’s map. There are state and provincial maps for the US and Canada. It’s easy to uninstall the maps that you no longer need to save space on your phone. I like it a lot. And best of all, it’s free.