Tori Spelling is smiling, but not because she has just heard about her spicy Beverly Hills, 90210 fall story line (a liaison with newcomer Jamie Walters). No, Spelling is tickled to learn that her manager also handles Lisa Rinna, who plays Days of Our Lives' Billie. ''Wow! I love that show,'' says Spelling, 21, who has been devoted to Days since she was five years old. ''I watch with my girlfriends,'' she says, insisting the appeal of the show is not the hunky guys. ''It's the stories. My favorite character is Jennifer (Melissa Reeves). I'm really upset she's with Peter. I want Jack (Matthew Ashford, who was fired last August) back.'' As for Rinna's current plotline, in which her beau, Bo, has met a woman who resembles his supposedly dead wife, Spelling says, ''I'm torn. I used to be a big Bo and Hope fan. But I don't want to see Billie lose out.''