I like to read a nice, big book every once in a while. George R.R. Martin's books are great for that because they are usually around 800 pages long (and because the books are amazing). My problem is that I have little patience and I want to finish a book within a week (max) and that just doesn't happen when I read a book from the 'A Song of Ice and Fire' series. I started A Feast for Crows in December and finished it early March. The reason it took me so long: procrastination.
I first tried to read a chapter a day but that lasted for a week... When I was about halfway through the book I was so done with being 'stuck' with this book that I looked for a different method. I counted how many pages I had left to read, divided that by 4 (a month is about 4 weeks long) and stuck 4 post its on the pages. My goal was to read until I hit a flag/post it and that each part was allowed to take a week. In short: read from flag to flag - every flag taking a week.
This finally worked for me! In fact, I got so motivated to get to the next flag that I ended up finishing the book in a week and a half. I don't know why I get so intimidated by these books (honestly, I only get this with GRRM's books) but I think I will use this method again if I feel like I'll be procrastinating again.
I hope this helped someone out. The size of a book shouldn't matter, you just have to keep it interesting. I made reading this book a game and therefore I had much more fun reading it. Let me know if you have a trick for getting through giant books.