Mine is a bit out of left field, I'm sure, compared to most others, because I like the classics mostly. But this is one almost any reader can enjoy - The Count of Monte Cristo. It got a new translation this decade, and you can get it for $4.70 on Kindle. New translations of old classics are rarely so cheap, and this one in particular is a great modernization compared to the old, musty 19th century translation from French. The archaic translation is the one you find in 99% of its editions because it's open source and absolutely free to publish.
But the Penguin translation really restores it to present day English. In short, pick this up if you want to read a story that was good enough to stay on top of the literary heap for 100+ years, but one that doesn't carry any esoteric literary baggage at all (no metaphors, no allusions, or social commentary, somewhat rare for 19th C. literature). The best of Dumas' works are all incredibly entertaining and hard to put down, and this one rivals The Three Musketeers as his best work.
Whatever you decide to buy, Merry Christmas, and enjoy your Kindle. I'm personally too attached to physical books, so I usually buy an edition on Kindle to match my physical copies and use it when I'm on the go. Either way, it's pretty handy.