Change granularity of date range?

I want to get a graphic of weekly visits on my site between november 2012 and yesterday.
It seems if I choose a “week” report, I only get weekly visits for the last 6 months or so. If I choose a custom page range, I don’t get to choose the “granularity” and results are given on a daily basis. This is harder to read and interpret because there’s a lot of daily variation.
Did I just miss how to get week-based reports in a custom date range, or is there just no way to get this?
Also I’ve been wondering if I could have a CSV export of the evolution data. It seems all that can be exported is the static summary.

Just found an answer for the second part of my question: exports do not give evolution data when “Date range” is selected, however they can be exported if “week” is selected.