There's a certain danger in giving books as gifts. It's the same problem that arises with recommending books. My mother kept recommending her favourite books to her book group, and no one ever liked them, so she just stopped recommending them. Our favourite books feel like ours, and suggesting them or giving them as gifts feels like offering up our own work for judgement. On the other hand, books make a convenient gift. You don't have to figure out what to give, just which one to give.
I'm a terrible gift giver. I make things for people because it takes less work and less thought than buying things (I know this seems counterintuitive). For most holidays and most people I just skip the gift entirely. But there are one or two people I'll give books to. It's only people whose taste I know extremely well, or people whose taste I think I have some chance of shaping.
The books I'm most inclined to give are those which I've found most readable. Not necessarily the best, but the ones I sped through and read aloud. Connie Willis is one author whose books I think would make a good gift. To Say Nothing of the Dog in particular--fabulous and interesting and lighthearted. Major Pettigrew's Last Stand would also make a good gift, and while we're on the name, Miss Pettigrew Lives for a Day.
Do you give books as gifts?