I am totally LOVING this thread.
My ex-wife and I broached this subject before we were even engaged; it was a lot easier to move forward knowing that she didn't want any kids for a few years after tying the knot as well.
Lazy Sundays lying in bed, reading the paper, enjoying "you" time? probably not so much after kids. As well as a ton of other things, most of which have already been mentioned.
I do have to add my two cents on the travel portion. I highly recommend involving the kids when you take trips, especially to really special places.
I grew up as an Army brat, so my sister and I were basically forced into traveling a lot at an early age. The ride was definitely not worth the price of admission (14 different schools before graduating high school. Ugh.).
HOWEVER... due to the travel experience, my knowledge of geography was miles ahead of most of my peers as early as 6th or 7th grade. Knowing that there's a hell of a lot more to the city of Amsterdam than hookers and weed takes on a whole new meaning when that comes from personal experience - before age 12.
Then again, you probably want to get that all-inclusive visit (or two, or three) to Hedonsim out of the way before childcare becomes a necessary expense.
It's all a tradeoff, but dragging along the kids will definitely pay off in some ways later on down the road.