We have a living room size 18x23 opening to kitchen and dining...we plan on putting vaulted ceilings a the living room and 10ft ceiling in kitchen and dining...Will it not be too high and uncozy?
"Vaulted" has different meanings to different people so you need to describe the ceiling design but I don't know what anyone's opinion would be worth if they didn't know considerably more about the design of the house. If you want an uninformed generalization, I would say that 10 ceilings are never cozy.
High ceilings in a kitchen always pose a problem for the design, sizing and installation of upper cabinets. Too many people just buy upper cabinets designed for 8'-0 ceilings and let them "float" on the wall, with exposed wall space above the cabinets. The result often looks like an unplanned "picket fence", with the tops of the cabinets perhaps unaligned and the faces often different depths, especially when it comes to hoods and/or refrigerators.
When faced with the blank space above the upper cabinets, some folks pile up baskets and other decorative objects giving further emphasis that the cabinets, walls and ceilings were never considered together.
You may wish to think about the design of the kitchen walls and cabinets before deciding on ceiling height.
Good luck with your project!