FNL was/is a great show. It is to bad that it did not really last. The problem with those shows is losing the characters because of "age", they start the show with everyone being juniors and/or seniors and then all of a sudden they are sophomores and juniors, but then they still have to graduate eventually and it is hard to bring in people.
That's what is so funny/great about 90210. First, they changed the group of kids from being juniors to sophomores a few episodes into the first season. Second, they made the brilliant move of sticking with the same cast and following them to college. They didn't make it about the high school, they made it about a fish out of water situation (the Walshes moving from Minnesota) and how they interact with the new people in BH and making friends.
The best thing that BH 90210 ever did was have those summer episodes at the BH Beach Club. They had new episodes during a time when everyone else was showing re-runs, so it really enhanced their audience going into season 2.