There's a Lost themed "Who would you save" ppt somewhere on waygook.

Students discuss advantages and disadvantages of the characters. You can get them to explain their reasoning and all that (get them to elaborate on their answers i.e. so if you choose this person what can they do for you on the island? Will they clash with another person you want to save?)

Also another I recommend is "Animal Wars" also floating around on this site

- sounds pretty brutal and actually does have videos of animals fighting but they're in the wild not forced to fight (with the exception of Bull/Lion). ANYWAY in this lesson the students predict what animal they think will win and give reasons for why they predict it (i.e. "I think the Bear will win because it's stronger" you can get teams to kind of debate too. And they bet which is quite fun).

Don't worry, it takes some time to get used to your students and to figure out what they need to work on--it's just part of teaching, and something that takes time regardless of what your background is.  I had a degree in Education and teaching experience in a high school back home before I came to Korea, and I still found that it took some time to figure out what works in the classroom here. 

I also work with high-level high school students.  I use conversation cards every so often, and I've found that it's a good way for students to get more comfortable speaking.  I just arrange them in groups and have them take turns asking each other questions (I cut up cards with one question on each card). It's really easy to find TONS of conversation questions online.  I usually start by introducing the idea of follow-up questions and tell them that for every question they have to 1)answer in a complete sentence and 2) answer follow-up questions from their group members.  Sometimes I pick a topic that I'll be talking more about in class (such as food) and make all the conversation questions related to that topic.  Other times I just put a bunch of assorted questions together and let them begin the class with some practice.

I also try to do some pronunciation exercises with my students.  Sometimes I just spend the beginning part of class working on a particular sound that I want them to practice.  Tongue twisters and minimal pairs exercises work well.  My students are serious about learning English, so they really put in a lot of effort and concentration when we do these exercises. 

 A lot of the stuff on this site is good, but not always aimed towards high-level students.  There are a ton of games on here, but remember that you don't always need to play games with them.  If you have high level students, just take the opportunity to do different things with them. Not every lesson will be successful at first, but just keep adjusting things until you find what works. 

I don't have very high level students, but here are some thoughts for you off the top of my head.

In terms of Lesson Topics, some that I've been wanting to try but need to work on leveling for my lower levels--

Debating
Story telling
Advertising (I LOVE the Inventions and Infomercial lesson ideas)
World Trade (http://www.waygook.org/index.php?topic=49476.0) - I have used this in camp and it's amazing. The kids get SO into it. But if you want them to speak English instead of Korean... you really have to pre-teach some terms and be strict about enforcing a no-Korean rule.
A lesson on the "Words" video (http://www.waygook.org/index.php?topic=8598.0)
National Geographic "World's most typical person" lesson
This one from breathy vowel: http://breathyvowel.wordpress.com/2011/05/28/questions-questions/

The way I see it, you can tailor your lessons a couple of different ways. You can keep doing what you're doing and use a lot of the standard topics from waygook---travel, shopping, sports, movies, music---some of which are really good---and just beef up the material. Throw in an idiom relating to the day's topic; get them to do more improvisational dialogue, rather than writing out or following a script.

Or you can really try to tap into their interest and creativity. Teach English through other subjects: Have a logic lesson, a few debate lessons, a math lesson (even high level students have issues with numbers bigger than 1,000!), an economics lesson, etc. Get them using their entire brains, not just the corner they reserve for English class.

I'd also recommend this site if you have reliable technology in your classrooms: film-english.com

Good luck and enjoy all the amazing banter that comes with high level classes!!

@ Denevius  I' taught elementary last year, so its quite a bit different going from a text book and co-teacher to no textbook and no co.