Scan resolutions like 75, 150 or 300 are useful.
If you don't want to zoom in a part of the scan, 
or print it in a high resolution the resolution 
mustn't be high. You can't see more than 75 dpi 
on the screen.

I scan the cel 1:1 and then scale down the scan. 
(scan is in 98% bigger than I want it)
Normal cels I bring at a width of 600 pixel
Cels with a background bigger than the cel => 
700 pixel
Oversized PAN cels get a width of 800 Pixel.

By scaling down the scan, the sharpness of the 
picture gets worse, most picture programs have a 
tool, where you can redo the sharpness.

Other points where I look at is the cel number. 
Often when I visit other galleries and mention a 
cel of the same sequence, I would like to know 
his / her cel number, but often it's not on the 
scan. So I try to get the cel number on the 
scan, too.

hope this helps a little bit