jane ny, I was in a similar situation last year. For me the sequence was paint first, then flooring, then baseboards, But it looks like you may have baseboards already installed. Painting first worked for me because I did it myself and there were spatters on the subloor before I was finished. You might want to check on whether your subfloor is indeed covered with plywood, because you may need an underlayment before installing your floor, depending on what you choose. Best to check where you buy the flooring. With some help from a friend who knew what he was doing and owns a Skill Saw, I installed a plywood underlayment in less than two hours. I too wanted tile with a slate or similar look, but the room was already over budget (long story) and I chose to spend my money on high end French doors because the floor could always be changed later. I got some advice from the flooring forum while deciding. You can always post a message there before you proceed. We narrowed floor choices down to either loose-laid sheet vinyl or vinyl tiles. My friend chose the tiles because the color and pattern seemed to fit well in the sunroom/porch. The original intention was to keep those tiles for about a year while I shop for tile and find a good tile installer. But the floor has held up well, despite some abuse like beach sand, rain coming in when some airhead (

I agree with the comments above that there are too many things on the dresser top. I think the colors work fine. If you want to see less of the green, you could put a dresser scarf on top of it in the same off-white color as the background of the pillow and then put your several low objects on top of that.

I think you have two options. The first is to get just about what you have now, except the interior will be white. I think the white interior will look nice. The second option is to build walls to accept new windows. I would get the windows to be the same size as the double windows and center them on the front facing wall. The siding could be wide exposure clapboard. On the gable end, you can do the same configuration or have two sets of double windows. On the back side of the house, you can do windows with a slider or a set of French doors. Going with option two will be more expensive, I imagine, but you'll be able to better insulate. You'll also have more wall space to work with. Here is my mock-up. (I also agree the shutters can go.)

Looks like a wonderful room to decorate! If it was for me, I would paint the whole room in white and use colour for accents, I show a few white sunrooms in white to help you consider. I did a floor plan based on your pictures since I didn't find it seemed conversational friendly. I would place a natural fiber rug to bring all the furniture together and also paint the 2 steps in white with a natural fiber runner (available at places such as Home Depot). I also show a console table behind the sofa to bring it forward into the room and closer to the facing loveseat. The rattan table lamps on the console and a black reading floor lamp next to the loveseat would provide lighting when needed along with the light on the ceiling fan (I show a more modern one). For accents, you can choose your favorite colour for accent pillows with you white sofa and loveseat, a throw, etc., here I show green accents. A few prints on the wall would also be nice. You seem to have white solar shades which are fine.