I can tell you that I love what we have going with Drupal at left-click.

The website runs the entire business. I'll try to rattle off most of what it does...

*Manages users, collects addresses, info etc
*adds repairs, onsites, websites, invoices, notes, tasks, special orders, etc, tied to client
*the clients user page is a dashboard showing only relevant data of the types listed above
*technicians/managers have different roles and their own dashboard (panels of relevant views) based on roles
*repairs are managed by workflow status and relevant emails are sent to techs and customers as the repair changes state, for example to "done" or "waiting for review"
*onsites show in a calendar view and an "upcoming" view on techs dash boards to which the onsite is assigned.
*onsite templates have google maps with A to B directions
*repairs and onsites can be set to RUSH status, SMS messages go out to certain techs
*websites have fields for most info you'd want to add, including a hosting paid until field, which puts them on a calendar telling you when they are due to pay again
*invoices are now done through ubercart and uberpos and repairs have a "create invoice" button which ties repairs to invoices and begins the create invoice workflow for the techs
*everything else (notes, tasks, special orders, etc,) has relevant views and is placed in the proper panels so the right users have access
*employees enter their hours everyday and the manager gets a view of reported hours and can filter by date range for reporting or to write checks for
*testimonials system, emails to client request them to give feedback to the testimonial system, they can create feedback as a user or anonymous, nodes are approved before published, also staff profiles can be rated by clients
*system has some cool graphs and maps of customers and products