I guess it depends on how much walking space you want. In this current configuration you have quite a lot of space for moving around, but do you want that? I would personally go for an L shape to maximise bench space with one section at a different height for seating. Alternatively, you could just have a standard L shape with seating on one side. Either way it's going to be quite a nicely sized kitchen.

A "butler's pantry" with a pocket door (and no sink, so more counter space) at one end of the kitchen would be the ideal solution, but of course that depends on dimensions of your kitchen and whether you can squeeze in enough space for that pantry. We have one off the end of our kitchen, which is maybe 1.5 m square and offers a lot of extra counter space out of sight of the lounge. We have friends who had a fairly big kitchen area, put a blade wall down the middle to create a U shaped kitchen, so the oven and bench face the lounge on one side of the U, the sink is at the end on the short side of the U, and the small appliances and pantry are on the other side of the U, with the blade wall hiding the mess.

yes that's how we've structured our benches at work..I've got the lower one as I'm only 5'2 and hubby and everyone else has got the higher ones

Find your basin first, and then calculate the height based on the height of the people in your house. (excluding the kids, they will grow). Rule of thumb is convenience of use and ability to look in the mirror without tiptoeing or bending down. Top of basin is usually 90cm (approx) for a above bench vanity, the table needs to be lowered. for a flush mount / undermount, then the bench will be at 90cm. My daughter is 150cm now, and 90cm benchtop works ok for her.