I usually have about 3 fiction books on the go because I like to pick something to suit my mood when I'm reading. A lot of what I read is a bit dark or strange so I often have a children's book or lighter more humourous one for when I can't sleep. Sometimes I get a bit fed up of one but not enough not to want to finish it so I might leave it for a week or so and start something else.
At the moment my main book is Doris Lessing's The Golden Notebook which I am enjoying and reading for 80-90% of my reading time.
Also being read are:
Lanark: A Life in 4 Books by Alasdair Gray. Good but the weirdness built up a bit too much and so this one is on hold for a bit.
Lives of Girls of Women by Alice Munro. It's short stories in a small format that fits in my handbag so this comes with me for waiting rooms etc.
The Fry Chronicles
The Parenting Book by Nicky and Sila Lee - just reading short bits now and then.