I have a bunch of uncovered windows. For The large ones I am thinking curtains. To take care of everything at once I though just use curtains for all of them. Though practically most curtains are only sold to cover something the size of a door wall. Is there a general rule of thumb for each and if I did go the curtain route is there any place that sells them at different lengths or am I going to have to cut them myself?
The current fashion (continuous since the 1980s) is distinctly for blinds.
I don't care for blinds as much as curtains: blinds are more expensive, provide less privacy, are more likely to break and harder to repair, don't provide as much sound or thermal insulation, and are harder to open and close quietly.
An eight-foot-wide by six-foot-high window seems to run about $1500-2000 for blinds and $200-$400 for quality curtains (plus $100-200 for mounting hardware).
Curtains are much easier to customize. If you are highly selective, you might want to find a professional seamstress to cut and hem a non-custom set. Or just take a whack at it yourself. This is hardly rocket science.
You can get custom made curtains in any size you want. They are also sold in different sizes from ones that only cover half a window to ones that will reach all the way to the floor and more.
If you find a fabric you like you can look for a local seamstress to make them for you locally if you don't have a friend or family member that likes to sew.
Same thing with blinds, you can have them custom made to almost any size you want.
Blinds get dusty and are hard to clean. My preference is for curtains that can be machine washed although cellular shades (honeycomb looking) can be useful because they have some insulating capabilities.