It depends how nice my children are feeling....
I get Harry Potters done within a few hours, I literally devour those books without regret. Magician took me a couple of days, I couldn't put it down and to hell with the children!!!
It does depend on how much I'm enjoying the book and what kind of time I have on my hands but most books, if I want them to be, are finished well within a week. The Farseer trilogy, like Teir was sped through, I couldn't put those down and I think I read all 12 books (Farseer, Liveships and Tawny) in a fortnight.
Still, recently, it's taken me nigh on 2 months to get Jonathan Strange & Mr Norrell finished and not because I wasn't enjoying it - I was, tremendously - but simply because I couldn't find the time and whenever I thought I had the time, my kids told me otherwise, often by snatching it out of my hand and throwing it on the floor!
xx