I think the one thing I miss is that Android used to have idle background battery usage estimates, so that you knew which apps were killing your battery in the background. It’s not quite as easy to figure that out anymore, but maybe something new will come along to help out with that.

I always use Franco Kernel Manager for this, along with Better Battery Stats to detect warlocks, in case there are any.

My device is rooted, but as far as I know root is not required to do this.