In fact, I think staying the night makes the most crucial difference...
For a touristy (and ZhouZhuang is the as toursity as one can get) watertown, those who have only gone for a day trip of a few hours wouldn't see the real face, and therefore the real beauty of it...
One would only say that not staying the night is no different from stay... simply don't know what they missed...
The first time I went to a watertown I went to ZZ... hated it until i turned around on the way to the tour bus... by that time all the other buses have left... That is the watertown I wanted to visit !!
In the morning... get up at 5 or 6 to catch the water town life that has been lived for hundreds of years, with all the old folks hanging out... and then it reverts back to touristyness around 9 when the day tours arrive to ruin it...
I don't have an inn in ZZ that I can recommend, but in TongLi... which is my favorite town and I have returned many times... I would highly recommend ZhengFuCaoTang, it has all the modern facilities and cleanliness, but looks and feel like a historic building...
If you are lucky the innkeeper-owner will come out and play his traditional Qin instrument in the moon lit garden... Very nice guy, just that he doesn't speak much English...
If you have friends who can read Chinese, check out the site...
www.zfct.net
Its prices are higher than the rest of the home-inns... when the other home-ins was 70 yuan / night it was 180 !!... Last time I went in June a regular "antiquey" room was 380 yuan / night.... but I still loved it...
Some of these home inns also operates a small restaurant with home-cooked meals... You also have to watch out for the cheap ones who quotes you a low price which DOESN'T include air-con overnight but only through to midnight...
Anyway, I really hope OP has a wonderful time staying over... wherever he goes...