For me, I always felt that I watched Beverly Hills, 90210 in spite of the character Donna Martin. In the early years, I watched the show for Brandon, Brenda, Kelly, and Dylan. Having Valerie replace Brenda easily made 90210 continue to be worth watching. And then Gina was a fantastic replacement for Valerie. What the show never found an answer for was replacing Dylan McKay. Luckily he returned for the final two seasons. His character was easily what made the show most enjoyable for me.