Suggestion for a quick refresh?

I just realized we're about ready for the next season and am feeling the need for a quick refresh. What would you recommend for someone like me, who

• loved and basically memorized the first 3 seasons, watching each multiple times
• found season 4 and 5 to be pretty meh, and only watched them once

I don't want to rewatch 4 and 5, but want to do more than just re-read a synopsis. Are there a couple of key episodes that are critical to the story arc? Maybe I'll just watch first and last of each of those seaons (I am rewatching season 1, just because it was so good)