My top tips for making mornings run smoothly are to have your partner bring you a cup of tea/coffee in bed first thing and, by the time thy're teenagers, train your children to get their own breakfast and clean up after themselves! Obviously this can take years and years, but if you put in a few years of getting breakfast for the rest of the family, it doesn't seem such a great ask to be given a hot drink of a morning before your DP disappears off to work.
During the transition years, when your children can do some things for themselves but cannot manage everything, have routines for school days where you oversee it all, but children pitch in helping in small ways according to their age and ability. Don't be tempted to start letting them help themselves to whatever they want (from cupboards) before they can wipe up crumbs from the table or load/unload the dishwasher!
Introducing a new task to a child is best done at weekends and holidays, so that they don't have to be rushed, and if it results in a mess it isn't an issue as there's more time to clean up. It also means they can still be in their PJs, so if butter gets smeared on a sleeve or juice is spilled on a chair, there's no need for a quick change of school uniform.
You could have children eating breakfast in their PJs every day, but if they are slow eaters and slow at getting dressed as well, there's a risk of making yourselves late, unless you are all very early risers.
Put the choice of breakfast ready on the table, they just have to eat it, put their plate in the dishwasher, help put packets and jars away and wipe the table.
Have everything ready the night before, including uniform ironed, homework done, forms filled in and cheques written, and bags packed, but involve your child in getting these things done, and by year 5 or so have them assemble what they need themselves. For example, for infant school aged children, put all the things to go into a packed lunch ready. They just have to get one of each thing into a bag (main, fruit, savoury snack, drink, dessert). By year 6, they should normally be able to get their own packed lunch (make and wrap a sandwich the day before, or ask for some extra pasta cooked and put it in a box) and cereal or toast for breakfast, clean up after themselves and check they have all they need and do most of the preparation the night before, asking for help if needed.
Everyone in our family likes different things for breakfast, so we rotate what is available. There's almost always a standard selection of toast and jam, porridge and a basic cereal, but I try to provide a bit of variation at weekends and at least one week day. I might do boiled eggs and soldiers one day, fruit salad with yoghurt another day, sausage or bacon butties, croissants, crumpets, English muffins, mushrooms on toast, pains au chocolate and pastries, smoothies, or pancakes/drop scones with syrup which is our favourite. It's a good idea to let children try different foods to see what they like, and have them try foods they don't like every so often, in case their tastes change.
My top advice on how to get children eating breakfast is to provide a lot of variety, and set a good example while they are young and eat something for breakfast yourself, with them, even if it is just a small piece of toast or a yoghurt or some fruit. If you're having overnight visitors find out what they like for breakfast beforehand, so your children see others eating well and it's just a normal part of the daily routine.