I only have knowledge of the Chesapeake, but second all that wwilson posted above.
There are outfits that charter boats in Deltaville, VA and while Labor day will be a busy weekend, the odds are if you choose something besides one of the 2 or 3 most popular anchorages you'll be able to find a place either alone or sharing with just a couple of other boats. For a 5 day charter you could choose to visit several of the Chesapeake classics like Onancock, VA, Tides Inn(Irvington, VA), Great Wicomico River, Tangier, VA, Mobjack Bay, St. Marys, MD, Solomons Island, MD. These are just a few of the possiblites.
As far as powerboats, I don't know exactly why, but the bay area near Deltaville is relatively devoid of the Cigarette boat crowd and the ratio is probably close to 50/50 sail to power. Most of the powerboats fall into the categories of Cruiser/Trawler, fishing or working boats, mostly fishing or working. As much as sailors love to slam powerboaters, I've never had much of an issue with powerboats around Deltaville.
s/v Palmetto Moon
1991 Catalina 36