Ok. So I actually am quite interested in what you did to get them to eat better.
Emily - well, I got a whole raft of advice from a lovely MNer with children who eat well and I adapted it to what DD is like. I'll introduce other elements as and when I feel it's time.
My first stage is that we have slightly more challenging things - for her - for lunch. If she refuses it, she doesn't get anything else until dinner time, except that I will let her eat some lunch if she chooses to do so. She's got the idea pretty quickly. Sometimes she eats, sometimes she doesn't. Dinner is something I know she will eat so I don't fret about her sleeping (she used to bea terrible sleeper too!).
Unless she eats a reasonable amount of her plate (I limit portions to let her have a chance at this) there's no pudding. Pudding is yoghurt or fruit.
Ideally, I don't show I care. I do blow this at the moment but am gaining confidence.
Spinach is actually something she will eat mountains of. What she likes is pretty healthy, but it has to be exactly as she expects it to be i.e. no lumps in a smooth soup, bread like I make it - not white or with seeds, no shard of onion or herb showing in a sauce (she knows it's in there: that doesn't bother her)etc... This even goes down to the brand of butter and olive oil I buy I buy.