Play with a D90 and a D3100 b4 you purchase. Having movie capabilities on the camera is always a plus. From the sound of things you dislike bigger and heavier apparatus so bringing the camcorder along sounds a little contradictory, however my iPhone does a better job on the movie aspect

... People always tend to forget they have a mini camcorder in their pocket at all times with all the new cool gadget mobile phones.
I did play with both and there are things I liked about both.
I rarely use video on my current cameras and when I do it never does more than sit on my computer. That said, with a baby, I expect video to be more important. But I still expect the camcorder to do most of the video, even if I only bring it along for special occassions or when I can through it on a stroller, leave it in the trunk, etc.
Thanks!
Scott