The short story "Firewatch" is also part of the Oxford Time Travel series, with connections to both Doomsday and To Say Nothing, but much closer in tone to Doomsday.

I also think Blackout/All Clear play better if you already know and love Colin.

I use the phrase "the Bishop's bird-stump" more than any normal person should.

I have a friend who rereads Doomsday Book every Christmas (except the past two years, for obvious reasons). I'm not that dedicated, but it's one of my most reread books.

To Say Nothing of the Dog is one of my comfort reads.

Last of the Winnebagos was the first thing I read by her, and it's probably the best story I'll never read again.

I like a lot of her other stuff, but those are my top three.