I would leave enough room so that when I turned on the faucet I was not at risk of splashing my hands onto the mirror. If the mirror is on a medicine cabinet, be sure the mirror, when opened, clears the faucet handle when "on" If neither one of these issues are pertinent, then I would be sure that there is room above the counter so the bottom edge is not exposed to water. We had a mounted wall to wall mirror above the vanity and it rested on the 4" backsplash. Over a few years the mirror delaminated near the faucet/sink wet area. The mirror would get wet and run down into the bottom space between the mirror and the top of the backsplash. It just got worse and worse over the years and because it was affixed to the wall, there wasn't anything to do but tolerate it until time to do a gut of the room. As far as width, that would be your personal preference. If the mirror is on a cabinet, will the door swing interfere with side lights?

Tell him to cap it the same way he'd cap the end of a piece of baseboard-- miter the end of the last piece of chair rail next to each side of the mirror, and cut a wedge shaped plug for the end, and then grout in the gap, just as was done at the end of the chair rail on the right in this picture:

WOW! Thanks everyone! You've been busy helping me! Thanks for all the great ideas, everyone. Sadly, les917, not all is going to work especially the furniture arrangement! :( The room is 13Â 6" by 18 4". The French doors arenÂt the front entry, its going toward the sunroom, the entrance/entry is the opposite side with the halltree! ha Let me give you the dimensions and see if you can make the arrangement but I can promise you it wonÂt work. I have been struggling and move them around for 10 years and this is far the best I can get. Dimensions: French doors are 6Â 5" Tiny wall next to it is 1Â 8" Fireplace mantel is 5Â 10" Window wall is 5Â The graduation pictures wall is 13Â 6" The tiny oval pictures wall is 2Â 4" The entrance towards the kitchen is 3Â 6" The anniversary wall is 4Â 7" The banister is 4Â 6" The entrance between banister and the wall is 3' 6" There are three entrances to this room (what a pain). The grand piano is 55" wide by 67" deep. It has to stay open for the better sound for he plays it everyday and teaches privately with his students 2 times a week. The sofa is 90" and the chair is 42" wide. The round end table is 29" diameter. The purpose of the dresser is where I keep candles and vases, etc. which I really donÂt have to have it. IÂm looking for a console for the right size to fit on that wall and IÂm having a hard time where now IÂd like to store music sheets/books. I did have it by the piano/stairway wall, it doesnÂt look right and made the entrance too narrow. The coffee table is 36" square (cannot get rid of if because we display our daughter whom died of SIDS pictures/items in there. I can get rid of the floor lamp if husband doesnÂt get upset (it was given to him from his favorite aunt) and there is no overhead lighting but those two lamps for the room plus the tiny lamp for the piano which does get pretty dimmed (I just bought the lamp for the round table from Goodwill and going to change the lampshade verily soon)! WeÂve been talking about putting windows on the graduation wall but have to save $$ first! Please get back to me and see if you have any better ideas with the furniture! I really appreciate your feedback! Keep it coming! Thank you. Thank you! Glad I become a member here because you people are wonderful! :)

This was very interesting...the very subject I was looking for. I also am just finishing my bath and have some nice mosaic tile left. I was thinking of just measuring the area of the wall that will fit the mirror (between the two light sconces) and then using two lines (or two inches) of tile frame around a mirror (I have many around the house that I can have cut to size). But now that I see the other options on here I was wondering...do you (anyone) think a round mirror will look okay using the same concept? I wanted a round mirror but I though it might throw things off...now I think it might actually add a lil something extra...