I've grown both.

Prairie Skies is a shorter, also finer textured grass than is Dallas Blues.

In order to avoid floppy grasses in my silty clay loam, I don't fertilize and I give little supplemental water.

Both grasses you've asked about will do best in full sun.

Thanks, Jean. Shorter is good so I might try PS although I like the idea of the violet panicles of DB. I guess I'll have to experiment if I want to see if they're floppy in my yard... still debating if I want to try that one at all...

I didn't know there was a grasses forum. So many plant obsessions, so little online time...........
:)