Growing up my brother and I always called my father by his (nick) name, Eddy. We always called our mother mommy/mom. The thing is that Eddy, sounds like Daddy and is kind of "cute" as opposed to mom's name (Charlotte) I don't know if my mom would have been upset if we called her by her name. Our friends always called them by their first names (instead of Mr & Mrs LastName)
We always called our grandmothers by their first name, but again, it wasn't like they were Gertrudes (or some other grown-up sounding name) They were Na (for Naomi) and Zan.
A few years ago, I started calling my father daddy. But I think it was b/c there was some weird stuff going on with him that really bothered me and by calling him daddy I felt less distant from him. I set up this weird block in my mind where I had to separate my vision of him as my father from the other disturbing stuff.
I hope my kids call DH and me dad/mom or some varient, and would encourage them in that direction, but if they don't I wouldn't be too upset.
But DH and I already call eachother mommy & daddy to our dogs (I know, we're freaks) so I expect we'll do with kids, and they'll get used to it. Actually, DH & I almost never use eachother's names, so I'm not sure the kids would have much chance to pick up on them. I am honey & he is bunny. So maybe the kids will call us that.
Also, (slightly OT- sorry if I am hijacking) but I HATE that my ILs insist that I call them mom & dad. Fortunately, it's in German, so I just pretend that Mutti & Vati mean something else. I already have my own parents!