You could try:
Printing to PDF then opening it in Photoshop - make sure you set your output to 300dpi or more so you can fiddle around with out loosing too much quality.
Exporting as a DWG - I think Illustrator can read DWGs, not sure how easy it is to edit them. can't remember though and no longer have access to Illustrator to find out. sorry. And I think Freehand can read DWGs as well. But again, can't remember. Years ago I used to import things from archicad into freehand, but I can't remember if it was dwg or eps. But what ever it was, it was editable, and good quality.
Saving as a tiff or a bitmap - they don't compress the same as a jpg (basically, jpgs are good for things with graduating colours, like photos and renders, gifs are good for block colours, like drawings, text etc.. and tifs, psd and bitmaps are better for both. but the file sizes are bigger.)
Save as a .psd - photoshop file.
When saving from a plan, zoom in and the quality of your saved image will be higher.
All a bit vague sorry, but hopefully some of it's usefull.