I've been watching mostly TOS now in preparing for STID, followed in the next few days by some of the TOS movies.
What I've done is pick the episodes that may have some relevance to STID, for example: "Errand of Mercy", "Day of the Dove" and so on because the Klingons are in the movie to some degree.
For the TOS movies, one of my uncles passed away last year, and he always found Trek things for me at flea markets and thrift shops. One of the last things he gave me was a box set of the TOS movies on VHS, and since I still have a player, I'm going to play the movies on that in honor of my uncle.
And Greg, I agree about interpretation of a role. Some folks should try to experience various interpretations of live Shakespeare. You will see 10 different people play a role and see 10 different interpretations. It's actually very interesting to see.