I accidentally read this at the same time as Uncle Tom's Cabin, which made for some interesting resonances - here, the Christians are very much the bad guys (and women), but people are again property, especially for sexual exploitation, and there is again a network to smuggle escapees to Canada. I'm sure that Atwood had Uncle Tom in the back of her mind as she wrote; I wondered also about Heinlein's Revolt in 2100 as a source (but it's a very long time since I read it).
The slide into totalitarianism is very fast - Gilead is explicitly described as late twentieth century at the end of the book (the suggestion being that it lasted only a few decades). The rapid transformation of the entire system of government of a superpower looked more imaginative in 1985 than it did only a few years later. I had forgotten that the terrorist attack which allowed the extremist takeover was blamed on Islamists, which doesn't look so far-fetched now but surely must have raised more eyebrows in 1985 when the book was first published.
I set off a debate a few entries back on whether "chair" is the first syllable of "charity", as Offred says in Chapter 19. It's clear to me that Offred is speaking in Atwood's own accent, where "Mary" and "Harry" rhyme (whereas for most English speakers the vowels in "chair" and "Mary" differ from those in "charity" and "Harry"). The setting is no further south than Washington DC, and possibly further north (the only other places mentioned are Bangor, Maine; Syracuse, NY; and Seattle). A friend of mine from Essex once told me, "I don' really 'ave an accent", and Atwood may have had the same delusion (I am sure it's been pointed out to her since).
OK, holiday over, gotta pack...