Our interior design company has just switched over to Archicad. We are really excited to get much more efficient with not having to do 3D models in sketchup and 2D drawings in CAD, especially on large commercial & office projects. Due to the nature of our work with the interior the tone and look of materials is really important. In sketchup we had the ability to adjust the materials in real time view of the model. I can't seem to find any info on how to adjust the saturation or lightness of a texture map in Archicad and have those changes show up in the 3D view. I know it is possible with renderings, but this is more to help us design while in the model, not to output images to show a client. I have read old comments saying the only way would be to open the image file in another editing program & adjust it there. Is this still the case in AC25?
Cinerender has a quick preview render window that shows the changes, perhaps this is helpful.
We do not have AC25 out yet in NL, so can't tell you if there are changes there in the 3D window (openGL) settings to manipulate textures.
The sunlight settings also have a big impact on how the 3D window looks. It is possible to have things look dark and murky or light and washed out if the settings for ambient light are too low or high.
Personally I see the 3D window more as a workspace with the textures more as a visual clue for patterns and Cinerender as my output.
Depending on your hardware, you can definitely make quick renders at lower resolution to get a feel for tone and look. Rendering marquee areas is also great for this.