Depends on the series really. Open ended series or series that end prematurly do that to me, but some that have really good ends that wrap everything up with satisfying results leave me totally content.
Best way to enjoy the series more is get tyour friends over and watch it with them. I'm the designated anime downloader in my group for beng the only onw with computer skill, so I always see everything first and then everybody else comes over to watch, so I always see a good show three or four times in a fairly short timespan. I get to enjoy them several times that way.
