I've been told that 'switchgrass', when mature (takes a few years to get to 3-6' tall), makes great cover for deer and turkey, etc. Anyone have any experience with it? How is it for wildlife? For cover?

Apparently, it is a prairie grass that is native to numerous parts of the country including the eastern part of the US. It also is known as wobsqua grass, lowland switchgrass, blackbent, tall prairiegrass, wild redtop, and thatchgrass.

One of the best nesting cover for all upland game

Yes it is good cover but it will take about 3 years to get high enough and thick enough to do much good for deer.

Pure switchgrass makes great cover, but it gets so thick that small game birds and turkeys can't go through it. It best mixed with other grasses and forbs which provide variety and browse as well. DNR around here had many acres of pure switch. They nuked it all and replanted with a mix. Now we've got deer and turkeys nesting in it. The deer are using it for browse in the spring. Some of those native forbs are the first thing to green up. A lot of fawns get born in the grass as well.

It works great for cover. Game birds like to nest in the center, and does like to fawn in it in the spring. However, it needs burning every couple of years to remove some of the old growth and open things back up a little.