Thanks so much for all the input. My "high level" simply meant I didn't need to know exact size of cabinets, placement of appliances, yet... Vickyw, extending the back 4' across current kitchen and breakfast is an interesting idea. My problem is that I have a walkout basement below so the 10' extension would get me a new full room in the basement but I'm thinking a 4' extension would be on posts and lead to a darker basement (I've got another bay window and duplicate of current kitchen window in the basement directly under the main level). I have thought of putting a screened porch off the bay window between the addition and the current deck so that the blank wall of the addition would be inside the porch. I'm attaching a rough layout that a kitchen designer did for the space (not to scale!). If the cabinets for the island were 18" instead of 24", there would be 42" in between island and cabinets in the area that extends into the addition and 60" between the island and cabinets/wall at the other end of the leg after it turns. A few more answers, the door from the garage to the outside will be on the far side near the front because of the slope to the backyard. The new master above will use the entire area above the garage including the new 10' and there would even be a storage area under the new 10' section of the garage accessible from the backyard (we have way too much stuff). We currently use the dining room as a "kid office" and have desks along one wall, storage cubbies, and a rectangular dining table (used to be Pottery Barn kid-sized farm house table but they outgrew it). I thought about moving the wall between DinRm and kitchen 2' into the kitchen to make the dining room bigger but since that wall is the middle of the house, I'm thinking there are cement support posts in that wall holding up the second level. What does everyone think of this layout?

@rrhaire, I think I still like #1 better. I like the 2 windows and I like that the toilet isn't next to the door. If you want a door in the middle-ish, I'd put the toilet on the left wall with the vanity between it and the door. Then I'd put the shower on the right wall. That would allow for a 2nd window on the left wall next to the toilet. That arrangement will give the spacious feel of #3 without requiring a privacy screen for the toilet that impedes traffic.

@scout It's not a 100% need, but it's a strong desire (especially from my wife) -- we're feeling like if we're investing in doing this whole project a bathtub is something we'd really like to have. We've been referencing this bathroom, also in LA, for size and it seems ours would be similar? I know to some this might feel tight, but this feels okay to me? So appreciate everyone's suggestions!

I thought the last two plans have the back door in the kitchen. Anyway, here are all the proposed plans with traffic patterns, prep paths, and clean-up zones. The first plan posted (whether the peninsula moves forward or not) is the only one with an efficient prep flow and no traffic through any work zones. Traffic to the fridge wasn't included because most of the plans have a beverage fridge on the bar run. I doubt the peninsula will be used for prep since it has no prep sink, but I added a sink and the green lines to denote that layout. I also added them in the second plan, as another poster suggested, but because the island is a barrier, IMO the prep sink doesn't add to function--and would put the prep zone in the basement traffic path. Even without direct access to the back yard, the first plan would be my choice. BTW, if the peninsula is only 3' deep, the seating overhang will be only about 10" since you'll need to account for a front overhang and a back cover panel. The NKBA recommends a minimum 15" overhang for seating at counter height, so an extra 6" depth would be more comfortable and would take up some of the dreaded dead space.