Painting trim the same color as a wall is a traditional and effective way to create a peaceful and airy space by making ceilings seem higher and simplifying things. I love it to get away from the look of white outlines around everything- a standard treatment but not always restful to the eye. Especially good idea for bedrooms, to allow furniture or art take center stage or if your trim is not that interesting.
My latest project, a 1940s lake residence has me thinking how simple design is often complex. There's little need to create focal points or add visual interest when this is the front of your house. However, it does not mean adding some "This Way To The Lake" pillows and calling it good. Furniture gets low to maintain sight lines to and through unfussy windows. Walls, trims and ceiling palettes should yield to the views beyond and I recommend a well edited but sumptuous mix of materials and neutral colors on furnishings to keep life casual without going nautical (blue and white) or tropical (any color with 'breeze' in the name.) The goal is not to mimic the water 'theme' when it's actually all around you, but to cultivate the comfort and relaxation that life near the water promises.
Nature just never gets it wrong when it comes to knowing what colors work together- especially for calming neutrals. Don't even get me started on flowers!