I've never worried a bit about how big/thick a book is, except when it's a paperback that's falling apart because the spine isn't tough enough. To me, if it's a book I like, there's just more to love.
I still remember that the library's copy of Gone With the Wind was 1020 pages, and I read it a dozen times or more as a teenager. I think of people who complain about books being too big as people who don't like to read anyway.
I've also read some average-sized books that should have been a lot shorter, so it's not so much the length that determines the fluff as it is, well, the fluff.