Check out Western MD. North Branch of Potomac (Barnum through Westernport) stays cold year round. Also have the lower savage right next to the North Branch. North Branch has wild rainbows, stocked rainbows, wild browns, and native brookies. North Branch also holds some monster fish. I landed a 21' brown in April while streamer fishing and my buddy landed a 24' brown right at the cabins in Barnum about 2 years back. The wild rainbows there are some of the hardest fighting fish I have every caught. Also have the upper savage and brookie tribs in the area, but those are probably too low this time of year. Even so, there is more water in that area than you can cover in 3 days.
Other options for trout is the State College area. I usually hit the little J, Spring Creek and Penns (all fairly close to eachother). I did a solo trip to state college in mid-april and had a banner couple of days, landing well over 100 browns (a few pushing 20' out of Penns). Not sure how it fishes in the summer.