I don't much like reading books about time travel. Mostly it just makes me dizzy, I don't deal well with paradoxes. I loved the scene at the end of the new Star Trek film when Spock I and Spock II do the Vulcan equivalent of snicker over Kirk's gullibility as to the dangers of time travel paradoxes.
There are a few exceptions, like Lest Darkness Fall by L. Sprague de Camp and Time and Again by Jack Finney. John Varley's Millennium is another that has taken up permanent occupancy on my bookshelves, and I've been puzzling over why.
I think it's because the premise for time travel in this novel is practical. The future is robbing/mining/harvesting/exploiting the past to save the future, to ensure the survival of humankind. It isn't a bolt of lightning or a self-induced hypnotic state, no, this time the future creates a time travel machine specifically for this purpose and none other.
The motivation is great on a character level, too. Louise and the rest of her Snatch Team are sacrificing their own lives for the sake of the rest of the human race, and FAA investigator Bill Smith's job and personal curiosity, not to mention his love for Louise, pushes him inexorably toward solving this mystery.
One of the best robot characters ever created in SF, and in the best self-referential science fiction tradition each chapter heading is a shout-out to that which has gone before, including on page 23 one to Robert Heinlein. I'm definitely feeling the love.
In fact, time to reread it again...
(The film version of Millenium, with Cheryl Ladd and Kris Kristofferson, isn't bad, either.)