Sleep is fine
I have a TiBook Rev. B and I never shut it down. I sleep it all the time. On a new battery (mine is down to about an hour on full charge, but about two years old...) I only lost 2% overnight. Commuting will be even less. I even leave a bunch of programs open to save time. I only restart or shutdown for system updates with it. The response time from sleep to wake is so fast in OS X.x, when in OS 9 it would almost have been faster to startup and shutdown constantly.
I also switch between wireless and ethernet between home and work, and the network switching is pretty fast. I have it set to look for wireless first and then ethernet, so I don't even have to bother with location settings.
cpjakes