I have this mouse:
Newegg.com - Logitech Performance Mouse MX and love the fact I can just put it on the charger and not buy batteries. It lasts 36-48 hours of use until it needs charged again. Every 2 or 3 days I charge it, but I work 10-12 hours a day on my PC. I had it replaced under warranty once and Logitech told me that it will last a week before needing charged if you only use it 6-8 hours a day.