Sometimes, poetry can be a refreshing interlude between big fat history books and engrossing, emotional novels. It's easy to put down a poetry book in between poems and skip any that seem too long or otherwise daunting and just stop if you don't like it. I'm stubborn about finishing books and put down very few that I've started. I even read "Ulysses," or at least, my eyes traveled over every word on every page — it's claiming too much to say I "read" a book that I understood so little of. (Do you know studies have found James Joyce's vocabulary was much bigger than Shakespeare's?) But I'll abandon books of poetry without a qualm. If you find you don't like a poet, you're not going to get much out of reading more of her poems. That's like forcing yourself to eat a bowl of rice pudding after discovering in the first bite or two you dislike it. (I love rice pudding).
So ... what was I talking about? Poetry. Yes, it's worth it, sometimes. I recently reread "Beowulf," translated brilliantly by Seamus Heaney, and it was so, so good, just like it was the first couple of times. I don't reread too often, either, but "Beowulf" can be reread every couple of years, I'd say, and enjoyed every time.
Also, I read a neat little book of poems called "Sleuth," by Elaine Sexton, a contemporary poet who has written a few slim books. "Sleuth" is full of brisk, poignant, personal poems — not too heavy, not too light but just right for half an hour or so. I'm not sure where the book came from — it's a paperback and it's signed by the author to someone else. But that's one of the pleasures of collecting books — these serendipitous discoveries of writings you didn't know you had that prove just right for the moment.