I also liked A Voyage to Arcturus, which has become a modern cult classic. It's probably my favorite book I've read for SE, though it might be a little heavy for a "beach read." [2]
P. G. Wodehouse is always a good bet for lighter reading. [3]
The Martian books are also light swashbuckling sci-fi. [4]
The Murder of Roger Ackroyd is considered to be one of the best murder mysteries ever written. [5]
[1] https://standardebooks.org/ebooks/lord-dunsany/the-book-of-w...
[2] https://standardebooks.org/ebooks/david-lindsay/a-voyage-to-...
[3] https://standardebooks.org/ebooks/p-g-wodehouse
[4] https://standardebooks.org/collections/martian
[5] https://standardebooks.org/ebooks/agatha-christie/the-murder...
A personal favorite of mine is Jules Verne’s Around the World in Eighty Days: https://standardebooks.org/ebooks/jules-verne/around-the-wor...