Earlier quoted context omitted.
I find TripIt pretty indispensable even if I'd love to give "notes" to the designers Maybe Expedia too though I often make the final reservation directly One of the OSM mapping apps. I use MapOut TripAdvisor and Yelp are "OK." Often better than nothing. Various carrier or hotel chain-related apps depending on your preferences
On a related note in Europe I tend to use their taxi apps instead of Uber. In Paris I used the G7 app because official taxis could use the HOV lane while Uber cannot. In Italy, I use the Freenow app as I found their taxis very affordable.
Usually just looking at that taxi area in arrivals at the airport you can figure out which app is the one most supported.