This is an Australian site, we work in centimetres. So 30" is 66cm,and 36" is 90cm. Assuming the oven is on the 18ft side, then I would definitely go 36". Do you get a 24" oven or 60cm oven where you are? You could install two 24" ovens. Then you only need to heat up a small oven for everyday use, and you have the option to run both ovens when cooking for a crowd. All the best.

without the plan of upstairs i'm not sure that my suggested changes to front wall will be suitable but instead of reducing the rear deck, taking space off the front porch would allow extra space for the kitchen without changing the front set back and, unless there's some special reason for the extra toilet could you consider different access to the downstairs bathroom to have a more private toilet with included handbasin with or without the extra sink in the dining area?.. there's enough space for extra storage for utility and dining area with a table for two in the kitchen and extending the floor of the deck to the rear and side fences would allow more outside sitting area

You could keep a picture there and add a second large portrait shape piece to left, or have a large wide piece to left, replacing current pic with a tall lamp or other item on dresser in corner to balance. Or just a slightly large where is leaving rest of wall clear noting it looks a narrow walkway

Working with what you have I would try moving the two seater to the left with one of the side tables to the left of that with the tall vase of flowers (or change out for a standard lamp). A side table on the right of the lounge without a tall vase then the lovely beige arm chair in front of the windows. Moving what appears to be dining chairs across the room At the moment everything is over crowded and pushed to the walls