Hi Sean -
I mostly fish the South Fork of the Shenandoah but also have floated around Harpers Ferry/Brunswick/Point of Rocks in my raft.
I'm definitely seeing more grass on the Shenandoah this year too, which could be I think should actually bode well for the fishing this summer. Not sure what's causing the grass (maybe slightly more rain than past years, timing of the rain, etc.) but I'm excited to see what it does for the fishing as we've had low grass years in recent history. Here's an interesting & pretty detailed article from Harry Murray on fishing grass beds that might be helpful:
Murray's Fly shop article
The South Fork is likely a bit more of a drive for you, but happy to give you a run down of some of my favorite floats as well as share what I know about fishing around Harper's Ferry (although I have floated that section less).
Shoot me an email and I'll send you my cell #, it's probably easier to chat through it.
Brian