large files

Here's the situation...I am creating 6 illustrations on 8.5"x14" paper which will need to be scaled up to 8.75'x30'. In the past I've scanned in the images, created work paths and scaled it up. It keeps the file size fairly small, but it screws up the line work.
So my question is whether there is any other way to do the above without screwing up the lines and still keep the file size to a reasonable size. Any help would be appreciated, and since this is my first post...hi!

Have you tried Adobe Streamline?

There's a recent similar thread about this here in the Adobe Photoshop section. Check about.

Peace.