I wrote a program that monitors battery state for Windows [1], and after a lot of research I concur with the other opinions posted here that leaving a lithium ion battery at 100% for long periods of time is not a good idea.
The software I wrote has configurable alerts so a user can get an alert then it's reached a certain change level (like 90%) and then again when it drops below a certain level. Users have specifically ask for that so they can unplug without over-charging.
Slightly OT, thanks for this software. When I picked up a new Windows tablet I was looking for a better battery indicator and found BatteryBar Pro. I don't personally use that feature, but it was something that I liked.
The feature to show remaining battery and charge time is what I really enjoy about it.
The software I wrote has configurable alerts so a user can get an alert then it's reached a certain change level (like 90%) and then again when it drops below a certain level. Users have specifically ask for that so they can unplug without over-charging.
[1] https://batterybarpro.com