I am unsure of how to obtain clean geometric areas of grass that are the same height and multiply them within the given area. 

I have several grass packs, but they are far more conducive to random natural environments and are a bit long for use in an architectural setting. I understand how to move them down and obtain a shorter length, but what I want is a thick manicured lawn that is defined by the perimeter of the area, not by the randomness of the grass sample configurations that I have. 

Seeing that I have a number of large areas, I would also like to know how one can mechanize or speed up the process of placing individual plant modules in order to fill up a given space quickly. 

Does anyone know how to do this?

 How about creating a another, identical, object that will be placed over the, say square area, of where you want the grass. Then place a grass eco system on that object, making it 100% density. 

Or, you could make those areas of your scene a little higher than the rest, place the grass eco system but make the slider for eco system just populate the highest area (also 100% density).

Hope this helps!

use a black and white distribution map to decide where the grass goes and where it doesn't

 For great lawans, check out solosplace.com. Pete's a very helpful fellow and I suspect he'll gladly share his technique. When he does, be sure to mention it back here!

-C

If it is looking too sparse remember that you can enter densities higher than 100%, you just have to put the number in the box instead of using the slider

Here's what I was able to come up with, I made an ecosystem material using Walli's grass pack 2 - the three grass patches, setting density to 100%, maximum size variation to x=0 (y & z are grayed out), drove the density with a crisp black and white image created in photoshop. The edges aren't perfectly square because the patches are somewhat rounded and irregular.

 Thank you to everyone for your suggestions.

1. Making an object a grass eco-system really doesn't cut it because it is populated with grass objects that are so irregular in character that they extend too far beyond the perimeters...unless someone is selling a grass pack I don't know of that is more like a single small cluster?

2. Frank T: I'm not sure what you mean by making a black and white distribution map, but I am guessing that I would end up with the same problem using grass object modules to populate it.

3. I checked out Solosplace and saw an couple of examples that do what I'm thinking, although I have to note that I've yet to see anyone do something on the order of a large city park with carefully cropped lawns and lots of defined edges....and Pete hasn't gotten back with me yet....

4. Sangelico: that looks good and would work, it doesn't have to be absolutely perfect straight edge, just one that doesn't extend a foot into the sidewalk! LOL If I could airbrush that on as individual objects onto the object as an ecosystem, that would seem to be the way to do it...do you have the address for Wallis' Grass Pack 2? I couldn't find it.

Walli has several grass packs available - I purchased mine at cornucopia3d. Good luck!