I like the Trends feature that allows you to pick a specific day, a portion of a specific day (<=24 hours) and then All Days. These are useful if you have a specific time period in mind and it allows you to narrow that window down as needed assuming it is <= 24 hours.
What I find missing & desired is the ability to look at the trends over greater periods of time but less then All Days. For instance, I'd like to display a trend that shows usage for the last 4 Mondays from 6am to 7am. I'd also like to display trends for the last 3,7,14 days. Another example might be trending my batch window (10pm-2am) for the last 3 weeks (M-F, excluding Sat-Sun). I believe the data is already in the repository, I am just looking for a more flexible way to gain access to it.