As someone that has seen all/most Trek in full (same with the B5 universe), I agree with this strategy, it's a great suggestion. They can always come back and watch the remaining ones later. I would reduce the IMDB rating threshold to about 7.7 though and they can apply that to season 2 and 3 of DS9 as well (don't skip s3x22 "Explorers" though, it's a good one despite lower rating).