Oooh, tough one Dandy. I tried to conceive DS1 for 2ish years and one of my friends used to ask me, with all the sensitivity she could muster, in a certain sympathetic tone, how it was all going. Sometimes it would drive me demented but at other times I'd welcome the opportunity to chat about it. I used to make a real effort not to talk about it for fear of becoming a TTC bore.
As for other people's children: well I must admit that prior to having children of my own I tended not to give much thought to them. So much so that I didn't even buy cards or presents for new babies because I just didn't know it was the done thing. My parents never bought cards or presents for new babies so it was only when I witnessed MIL doing it that it twigged that all those rows of new baby cards were there for a reason! I do feel guilty that I never asked after my good friend's 3 children during long phone calls and I fear she must laugh at me now as I try and make up for it.
I must be honest and tell you that whilst I did feel a pang of envy when I heard of friends becoming pregnant, hearing about children never made me sad. I think in all honesty when I was TTC it was all about the process rather than the end product, IYSWIM. But we're all different, I guess.
Much waffle. Sorry. What irritated me more was people telling me stories about friends who managed to conceive after going on the IVF list or whatever. Or telling me to take a random herb, or acupuncture, or yoga, or whatever.