We extended downstairs some years ago and now have an open plan Kitchen / Dining / Lounge Area, incl kitchen counter and island.
These were 2 separate rooms and so now we have 2 apex / hipped roofs. If you can imagine, 2 oblongs with a semi-hexagon on each end, side by side. We have 6 spots in each oblong and 3 in each semi-hexagon, all on separate switches.
The best thing we did was also include Lamp sockets that can be turned on from another light switch, 3 sockets in each semi-hexagon. We have 3 spearate light switches in each side of the downstairs extension, which covers all the possibilities.