We put our microwave in a cupboard, regular one nothing fancy, as it used to be in the hallway in old kitchen (tiny kitchen is tiny), apart from the very odd time when forget to leave the cupboard door open to vent it, zero issues, love that you don't have it hogging up a huge chunk of worktop (attracts filth and clutter, ever seen a kitchen without something sat on top of microwave?).
Only have a single oven, and a bit of a pan drawer underneath it. At time we wanted maximum storage so opted out of a double split oven job in favour of a pan drawer. Turned out we went overboard on storage, now have THREE places to store pans and trays, under and above a full height built in fridge (under is big, above it is fecking massive, 600x600x 400 high) so COULD have gone for a double oven.
For me, 2/3 main oven + 1/3 smaller oven + small microwave in a cupboard is the ideal (which wish had done). You don't often need that second oven, maybe a few times a month, but you do miss not having it. If for nothing more than heating plates