We are building a new home. I plan to have a smooth surface cooktop. I am trying to decide between a wall-mount microwave/oven combo versus a wall-mount oven (with possibly a warming drawer under) and a micro-hood over the cooktop. I want to stay with the current "style", but not sure which would be the most up-to-date. Also, not sure how effective a microwave/vent hood is for removing cooking odors as we will have an open concept for the den/dining/kitchen area. Any thoughts?

Microhoods are not as powerful as other forms of ventilation--if you cook frequently with all four burners going--or if you have more than 4 burners--go with a vent hood.

That said, it's possible to get a double wall oven set up where one is a traditional oven and one is a combo microwave/oven--if you have room for that, all your needs would be met.