A book series you wish had gone on longer OR a book series you wish would just end already

Today begins the thirty day blog challenge developed by Blogs of a Bookaholic...  In some ways, this question is one of the harder ones for me to answer as I don't tend (on the whole) to be a series reader.  I suspect that my answer may then be slightly predictable.  At the time, I loved the Harry Potter series and wanted to remain immersed in that world over the long haul.  I loved that J.K. Rowling created a place that I longed to visit every few months.  That said, if she were try to bring it back now, I think I'd be less impressed.  I think I'd view it as a desparate attempt to recapture something that should perhaps be left alone.  That moment in time is over.  Someone should have told this to George Lucas!