For my money, book covers are the site of some of the best graphic design and illustration that you can find today. Here is a shelfful of nifty ones. Go ahead, judge the book.
Speak Memory, designer Michael Bierut
Loneliness, designer Peter Mendelsund
The Periodic Table, designer Jim Friedman
Columbine, design by Henry Sene Yee
Penguin Book of Gaslight Crime illustration by Jaya Miceli
The General Theory of Love, designer John Gall
The Music of Chance, designer Yorgos Marinoglou
Then there are the books that seem so complete that nothing else is needed on the cover but the title and the name of the writer. Cited here.
And if you don’t like the cover of a book you have, you can make a simple paper “jacket” of your own from plain paper.
And maybe add the title and author. Hey it’s your book.