Queen of the Slayers by Nancy Holder
My guilty pleasure--Buffy the Vampire Slayer. I was 45 years old before I found it. It's a very witty program.
The book was pretty good. It picked up right after the TV series ended, but it doesn't have that Whedon touch. This is the first book I've seen based on the series, but Holder has written dozens. She did a good job on the characters. I could hear some of them as plain as if I was watching them. But at times she throws in little things from the series as if she's trying to prove she watched it. Sometimes they were totally unnecessary.
The premise is set after the Hellmouth is closed. All the demons are P.O.'d about losing their favorite lair, so they're raising a ruckus all over the planet. And turns out the Borgia's were vampires who wound up trapped in another dimension and are trying to get back to rule Rome. A distant ancestor is dating a girl who is now one of the potentials. And she decides she wants to be Queen of the slayers and begins gathering girls to her side. So Buffy and the Scoobies are spread between Ohio, England and Rome trying to get control of the chaos.
It's still goofy, but it's great fun.