I marked about 200 spots on Google Maps for my trip last month to Iceland. I created a 3 minute tutorial on how to create the POIs using Microsoft's Screen Recorder utility. The video shows 3 ways to mark a spot/POI. (1) using the search feature (2) typing the lat long and (3) dropping a pin. View the video in full screen mode so that the map resolution is the best.
This is how I used the created POIs.
1. Download the POI file in kml or kmz format from the Google Maps app.
2. Imported the kml/kmz file into the POIViewer app on my iPhone6.
3. I also downloaded the Navigon Europe map app and the Iceland map from the iOS app store. I used Navigon so I dont have to incur data charges while in Iceland. Also, Navigon will work even when there is no cell phone coverage.
4. I selected the next POI to visit on the POIViewer app and then asked it to navigate. It opened Navigon and routed me to the spot.
The tutorial is at
https://dl.dropboxusercontent.com/u/6804276/Screen.wmv. Enjoy & let me know if u have any comments or questions.