Reading commentaries is an opportunity to watch someone with a lot of knowledge and experience interpret a text. If you're a Bible teacher, an opportunity to watch someone open up a passage and explore its depths is a great way to become a better teacher; we can learn a lot by watching others. Commentaries spend a lot of time with the text, and that means when reading a commentary, we will spend more time in the text. That can only be a good thing.
There are various levels of commentaries, and I find the site Best Commentaries very helpful for identifying them. Commentaries are identified according by a "T" for technical, "P" for pastoral, and "D" for devotional. The pastoral and devotional type commentaries are probably the best for general reader. The site also links to locations to purchase books. I discovered a very helpful feature here: I was able to use the links to help me find which local libraries hold these books. Tim Challies' commentary recommendations and Ligonier's recommendations provide helpful input as well.
Before your purchase, read reviews or ask someone who has read the book. Sometimes, not everyone reacts the same to a commentary. I bought and read the Reformed Expository Commentary on Ruth and Esther because it came highly recommended, and I really didn't like it. It's frustrating to invest in a commentary you think you'll never read again. I am going to make some recommendations below, but don't just take my word for it; ask others.
Another reader friendly series is the NIV Application Commentaries series. The layout of these is really good. Each passage has a section discussing Original Context, Bridging the Contexts, and Contemporary Significance. I don't regularly use the NIV, but the text is printed in the commentary for ease. Karen Jobes's volume on Esther is excellent, as is David Garland's commentary on Colossians. These volumes also include a select bibliography, which is a great way to find out about more commentaries on the same subject.
Commentaries will get you thinking. The writers will point out things you may not have noticed. They may have explanation about the cultural context of the book which provides insight. Reading a commentary along with daily bible reading means we may slow down a little. We are often in a rush to get to the "application" phase that sometimes we don't interpret carefully, and that can lead to wrong application.
Commentaries help me a great deal with preparation for teaching, but they also open up God's Word to me in deeper ways. Even in the midst of a more technical (e.g., D.A. Carson's commentary on John) commentary, there are wonderful insights that enlarge our understanding about God. They may not seem like holiday reading, but you may be surprised.