Ideas for low but full plants
 

I've seen these tanks that look like they have long grass, 4 inches tall maybe, almost all over the forground of the tank and it looks great! I'd like something that will grow fairly quickly and not require a whole lot of light since i don't think it will get much through all of the my other plants especially once they fill in. I had swords in my old tank so full that you almost couldn't see anything from the bottom 6 inches of the tank. I split them with my neighbor when I changed tanks and didn't keep enough for myself so I have to start over again!

Dwarf sags and micro swords come to mind with the description you give. Some species of najas are also used in the foreground. This plant can achieve a carpet effect when kept neatly trimmed. Some even use java moss.

Echinodorus Tennelus can grow low and grows fast enough to form a sort of carpet. I have heard it is hard to control but might be worth a try.

The micro swords for sure. But I have heard they require medium or higher light to grow. I tried it once and with my standard hood at 15 wats on a 10 gallon it turned yellow and died. Might be able to now with over 30 watts but haven't tried it again.

Dwarf Sag is the way to go for a grassy lawn. Another thing that you can do for a lawn like effect is to cover slates with javamoss and lay them on the substrate. In the past I have recommended using needlepont grid for this, but the neat thing about using slate is you can pull it out of the tank and hold it upside down over a tray to trim the moss to a uniform height.