

Just remember if you make blue print a grey scale everything blue will print that grey. I like to print all 5 grey colors out and then write which color those actually are in model space to make myself a little cheat sheet until I get used to it. It takes a while to remember which colors are which gray scale. If you do set up a plot table, I'd pick maybe 5 grey colors at most and set them to colors. I avoid this as many people can't follow directions and you will still get calls asking why your drawings don't print right. The reason I don't like to have a custom plot table is if you send your drawings to other people you need to make sure they have that plot table or when they print it won't look like how you want it to look. You can set it so all lines that are drawn in one color will print in another color(grey you pick). To do this you need to make a plot style table that has that in it.

I missed that you said you wanted to keep the colors but print in grey scale. You can open up the color you want to change click on the slider bar and keyboard arrow up or down the slider. Doing it that way it's easy to lighten or darken up a line. To keep it simple and less confusing I always use the same 3 numbers.

True colors print color even in monochrome so it forces it to print the grey I pick. For things I want a grey shade I use true colors. All my color lines in model space we use index colors. The way I do my grey scale is we use the default monochrome.ctb for most everything. If we do, it is just for a sketch up model to show a client a rough design so they understand it better. I've never found a need for that but that could be one use. You might want to change a color in the enlarged version. Like you have a full floor plan in one viewport and then in another you have just one room of that floor plan at a bigger scale. I've never used the change the color in viewport, but I guess you could use it if you wanted to changed something in just one viewport but not all.
