Our last home before this one, I had a favorite nook: It was one of those dining-room-type two-walls-meeting-at-an-interior-corner (the previous folks had a TV there), and the walls did not go all the way to the ceiling, which was peaked and quite high.
Paint: Suisse Coffee, which was a clean buff color, not dark like it sounds -- a calm neutral. The nook had double baseboards and two layers of moulding (might not be the correct term -- two layers of baseboard, but at the top!) that I painted in matching soft greens. At the point you might have a chair rail, I took a stencil, just three rows of little squares, and stenciled it a little darker than my baseboard colors. (More money, I'd have had that chair rail.)
Walls: I found an ornate plate display shelf, about 2' high and 4' wide, and filled it "to the brim" (!) with teacups and saucers I'd picked up (all second-hand happy little things, one pink with a ceramic rosebud rising from the rim of the saucer, and the cup was bell-shaped like a flower with the handle an extension of the greenery, quite impractical). I really wanted a cottage-view window there, so on the remaining wall, I took a 3' wide x 4' high Michaels poster of an English garden with a little flagstone path leading outward, and fixed it to the wall. Painted balsa-wood, or something equally light, squared "strips", and nailed them over the poster like a window with four "panes". I tucked silk wisteria or some such thing behind the left bottom & side window strips, as though the window was open and the flowers were tall and falling in. Then I pounded up a curtain rod at the top, one with about a three-inch clearance from the wall, and hung those curtains that have a lace-like picture woven into them. (Mine were bunnies.) That wall had a switchplate, and I found a three-dimensional bunnies-frolicking one -- kind of Beatrix Potter woodsy, not cartoonish. My floor lamp was cheap, but looked Tiffany-like, with panels of pastels.
Furnishing: One plain wood table (IKEA cast-off), four KMart chairs, a clearance layaway steal, varnished wood seat with hunter-green high simply scrolled backs and legs. Tablecloth, leaf-green and ivory plaid with a who-cares torn fringe (may have been from Pampered Chef -- that was the splurge). On the table, on a hand crocheted second-hand store doilie (sp?) was a yard-sale planter that looked like a wine keg with spigot (I kept a showy live pothos there) and a couple of fake clusters of grapes stuffed around the keg legs. Atop the high walls, I had baskets of the same size but varying in weave (about $2 each from a plant shop), with live pothos and ivies. Among them, I had little birds that were crafted so they looked real, except for their little flowered hats... a couple of birdhouses, one of which looked like a yellow-roofed church... and a couple of old granite-wear looking jars, tipped over. Somebody gave me a sign on a tall picket fence stake, shaped like a teapot, splotched with pastel flowers with raffia trailing from it, and black calligraphy that read, "Tea Shoppe Open". I nailed that on the end of one wall (about a 6-8" thick wall), and it stuck out, highly readable, several inches on either side.
People rarely sat there unless we had a lot of people over, but everybody -- mostly me -- loved that little "room". (Strikes me that this isn't exactly art, but it was the artiest place in my house!)