When I traveled to India for 3 weeks, I used Tripomatic (now called Sygic Travel) to plan each day. I got quite a few recommendations on what to go see when I started planning. It's really helpful with the map feature, and you can organize your trip however you want. The route mapping is really helpful, and it can help you decide how many things you should do in a day. You can share and collaborate with your friends too. http://www.sygic.com/travel
I was genuinely surprised with how well the Google Trips apps was thought out. The recommendations are great as well as the offline-first experience, but also the integration into other Google apps.
The travel guides in Google Trips are an awesome place to start. I helped my parents plan travel to Europe in half the time it normally takes me time to research things to do. They have suggested itineraries and you can customize things when you're there. A tap of the magic wand when you're on your trip, and you can find cool things to do nearby.