Hello!
I'm going to develop this project with Yii Framework and Yii-based extensions, like [login to view URL] Extension and others. This provides quick development, however quality is still high.
I've done same projects with Google Maps API, so I know what to do. Some kind of example is [login to view URL] (it's on russian, but you can see general usage of maps there)
The only question is design, so we can discuss it (like you'll show me examples of "good" and "bad" design) and start development ASAP.