This. Was not easy.
I used the same method of trimming the windows as I did over the doorways
HERE.
First, here is a picture of the finished product... it was really hard to get a decent picture with all the light coming in the windows and my cheap little camera.
Here is what it looked like before.
As you can see, there was nothing fancy about these windows, zero trim, basic baseboard.
I began adding the mdf, but here is where I got stuck. There was not enough room on the inside edge of the window for the full piece of vertical trim, because that's right where the wall bent. At first I started to get all creative with it but quickly decided it wouldn't work.
I ended up using a narrower inside piece hoping it wouldn't be too noticeable, and guess what? I think it looks fine! I don't have a table saw to cut the mdf down, so I used a narrower piece of trim I had laying around and just made do. Because that's what I do. :)(Refer to #2 above)
I had to do the exact same thing in the other corner of the bay window.
I continued the trim down to the floor where you can see I added a small piece of trim to the baseboard to make it a little heftier, and vertical trim underneath the windows.
Sorry, so dark!
Then I continued with the board and batten on the wall.
The crown molding that I used over the doors was too big here, so for these windows I bought the smaller crown, and good thing too, because they barely fit next to each other!
The other side was even closer! **And I don't know if you can tell, but I had to get extremely crafty while cutting that return piece of crown back to the wall, can you see how the wall curved there? Tricky.
A little caulk and a fresh coat of paint and wa-la!
I love the difference!
Not sad about seeing the gold and brown paint go, either.