You could set up Google Analytics for them. There's plenty of explanation per page of what the information is, plus pretty graphs and charts for the clients to ogle at. Alternatively for an onserver app then Tracewatch is quite good and free. Needs PHP/MySQL to run.
In the past if I wanted to give someone access direct to AWStats you can either give them the direct link and the login (and don't mention cPanel), or perhaps set up a subdomain redirect eg.
http://stats.domain.com and set that to redirect to the AWStats link.