Big Chill is ok. The first year I went the toilets were truly awful but they have worked to improve that and now there are more plus they are cleaned more regulary. They also have some hot showers which are good but there are queues... Not so many "shops" like at Glastonbury so make sure you get your supplies in advance.
I think you have to get there fairly early to get a spot in family camping as last year we couldn't get in, but we did arrive on the Friday. There seem to be quite a few kids things going on.