Hello there!
I have worked with the Google Maps API quite a lot, especially with sea vessels locators, which was based on actual GPS coordinates rather then actual addresses. There are some issues with accuracy of addresses.
I need to know what is the back-end of your website? PHP, Ruby, .NET?
Also you should know that there are limitations on a free version of the Google API, so depending on your load, it may be necessary to get the subscription.
Essentially, for you to understand, the process of getting the map on your site entails constructing a very-very long link, which includes parameters of all the relevant locations and pointers.
In any case, let me know if you are interested to talk it over.
Cheers,
Denis