I watched ESB in whole just a couple months ago, with the commentary track on to try to find things that might need tweaking for ESB:Revisited. I watched ANH:Revisited just before the XVID came out, and maybe once on DVD-5, but not the DVD-9 all the way through.

Other than that, the last time I watched the movies completely through was my sophomore year of college (2002-2003) to show them to a friend who hadn't seen them all. I started with Episode I and II, skipped III because it didn't exist yet, then watched the OT over the course of a month or so. I guess we also just watched the 97 SE tapes since the DVD wasn't out then.