How do I paint 2 rooms (kitchen and great room) 2 different colors when they share the same walls and there isn't anything spearating the rooms?
I wouldn't. If you have two walls that face each other which run from one the kitchen to the greatroom , I would paint those two walls the same color.
But the remaining two walls, (if I am picturing this correctly) could then be painted in colors that compliment the first two walls.
Look at the ceiling and that may determine separation..
or.. a Kitchen cabinet and sliding glass door or french door may be a good point to separate colors...
also.. sometimes the kitchen may be satin or semi-gloss - enamel. and the great room may be flat type paint..
hope this helps
How creative are you? Have you done much painting before?
The reason I ask is if you are any good at blending colors, you could create an awesome effect. Go ahead and paint each room the color you wish, leaving a little space between the two for the first coat. Then have a friend help you roll the second coat, adding a little extender (stuff that slows drying), and when you meet in the middle, over-roll into each other's color repeatedly to get a nice fade. This actually works best if you are ragging or sponging a finish, it tends to make the blend smoother. That's the nice thing about paint - you just keep working it until you get something you like.
I did my kitchen/dining room floor in a fade using industrial weight tiles, starting with a dark and light gray in the kitchen area, and changing colors of the dark gray to a medium gray, then a pale green, medium green, then forest green. The room was 40 feet long and 20 feet wide. If I had gone with one color it would have looked like a cafeteria. As it was, if you stood in the kitchen looking to the hall, the floor looked green, but from the hall it looked checkerboard - a VERY cool effect!
Have fun - it's only paint!