I have a window that is about 114 inches wide (made up of 3 windows like yours), maybe about 54 inches long as well. I currently have wood blinds, outside mount, and I do NOT like them. I am going to replace them with curtains . . .I just need to sew them!

Here is why I don't like them:
(1) You will be getting 3 different blinds, one for each window. There is no guarantee that the blinds will match up perfectly. I called the co. to complain, and they said it can be off within a certain distance per their standards, and if it exceeds that, the would replace them . . .but it was within that range, so no.
(2) Open, the outside mount doesn't look so bad. Closed, yuck! I think it looks messy.
(3) On a large window, it's a whole lotta blinds going on. Very, very angular, a lot of lines. If you were going with an inside mount, at least you could put curtains up to soften the edges, but with an outside mount-- not so much. On mine, the blinds are connected to something that looks like moulding, so I guess you could put up a rod that projects past that for a valance, but like I said, with an outside mount, panels would be harder.

Just my 2 cents. I know some people who visit LOVE my blinds, so who knows. When I got them measured, I had it done professionally. People will come and give you free estimates and do measurements then.

Hi I also have a window like that. I would suggest a bamboo blind with a valance and side drapes. Take your curtain rod all the way to the ceiling it will give it height Then put curtain on either side .About 45 inches wide. It will make it grand looking a great focal point