See if the manufacturer imposes a limit on how wide they will make a blind. I think there is a practical limit. I have a large window also but mine is divided into three segments (I think the total width is over 100"). I have three different shades, not on the same headrail. There are also limits on how long a headrail can be without incurring extra shipping charges. However, I like being able to operate them separately.

If it's going to be hard to reach the cords to raise and lower them, spring for the motorized shades. Definitely adds to the cost, but a great feature when necessary. We have had ours a couple years and have only charged them once a year. We don't raise or lower them everyday. Ask the manufacturer how often they recommend charging if you get motorized.