what to feed them ?

This is the topic of tomes and tomes of literature, but what I'm asking is 'what do I feed them?' within a context : Mummy is training really hard at the moment, I have no interest in big meals. Daddy comes home late and eats whatever is on the plate. Altho' my boys both eat well, and (here's a pat on my back) love fruit and veggies, I am concerned about two things :
1. quantity
2. time of day
Our youngest eats like a ravenous beast in the mornings. His first words EVERY MORNING are, "Mommy, pl'can I have some breakfast ?" which is so endearing. He takes his slender little frame downstairs, plonks himself on a chair, finds a bowl and proceeds to have 3 bowls of cereal. he doesn't always have the same thing - he likes Coco pops, he likes Weetabix, he likes Rice Crispies, he likes a bit of toast and jam, he likes porridge, he even likes All Bran Flakes. Sometimes he'll head off after that have have a nectarine, munch on an apple, or even beg for some yoghurt.
Our eldest is not the hungriest hunter at dawn. he's happy to have what the youngest is having (sibling rivalry and competitiveness is alive and well here), or what daddy's having - which is ALWAYS All Bran Flakes.

At lunchtime during the school week, I have learnt that I must not offer too many options. If I make the sandwiches and they choose which flavour of juice or yoghurt they're getting, that's quite enough. the youngest is not a big cheese eater. the eldest goes on cucumber sandwich eating binges. They often spot something in someone else's lunchbox that looks enticing, but once we buy it and it appears in theirs, their tune changes. sigh!

Dinners... (more to come on this)

I always have a big bowl of fruit in the kitchen - and I've always said, "help yourself anytime". It means we get through bananas by the dozen (usually over 2-3 days), apples in tens, grapes by the bag (I buy them in pairs now), nectarines, plums and peaches by the punnet, and other speciality items go down with varying success. Mangoes are a big hit. 'nuff said.

The youngest loves yoghurt, and that is often the only way to get him to eat his dinner. He is also a grazer, so will come back to his plate a few times before finishing it in the evenings. It's a tough one because I do want them to stay at the table until the meal is finished, which is impossible with him. the eldest is a great eater, and he'll eat all his dinner and ask for seconds often. he loves baked beans (I never did).