The icons that come with Google Maps are limited in number and in quality. While adding Google Maps to my site I was frustrated by the choice. Google Search came to the rescue, and led me to google-map-icons:
Happy mapping!
Some of my favorites are:Map Icons Collection is a set of more than 900 free icons to use as placemarks for your POI (Point of Interests) locations on your maps. You can use them on Google Maps with the "My maps" feature, or automatically by using the Google Maps API.
Happy mapping!