It wouldn't be right to talk about Garter Stitch without talking about Elizabeth Zimmermann, who was pretty passionately against purling and who gave us so many interesting things to think about and do with Garter Stitch (example: Baby Surprise Jackets).
In the 1970s she wanted to write a book devoted to Garter Stitch patterns but her editor didn't think a book on a single stitch would sell well. Of course now the knitting marketplace is full of books that drill down into specific niches, so its no surprise that her family has produced the book she always wanted to write: Knit One Knit All.
The book includes patterns for hats, mittens, sweaters, jackets, vests, baby things and more, knit mostly in Garter Stitch. But that doesn't men they're at all plain or simple. There's a lot of knitting origami happening in these patterns, and the interesting construction methods might draw you in to patterns you might not otherwise be interested in. I, for instance, am not sure Garter Stitch gloves would be that comfortable, but I'm way intrigued by the sideways method used to knit a pair in this book.
This one is definitely worth checking out if you're a fan of Zimmermann or of Garter Stitch. Or both!