I just finished reading "Gardening for a Lifetime: How to Garden Wiser as You Grow Older" by Sydney Eddison. It is available on Amazon.
The author has a huge property, but many of her decisions can be applied to the smaller garden. The book deals with the decisions she makes as she gets older to decrease the amount of work needed to maintain her large garden.
She has a very easy-going writing style and I enjoyed this book very much.