Ted from Munhall, PA on 2/28/2019 9:30:17 PM:
Indeed the weather and trail conditions are quite variable in April as others have responded. Indeed, the temperatures can be quite varied as well as the amount of precipitation. As for a "halfway" layover, Cumberland, MD at mile 150 of the 334 mile trip is the most populated town on the trail between Pittsburgh and DC. There is a Fairfield Inn (one of the Mariott brands) immediately adjacent to the trail that might be a welcome respite from the trail at that point, especially if the weather has not been or is not ideal. There are a number of shops, restaurants, etc. within a few blocks of the Fairfield. It is a little pricey albeit perhaps not coming from MA.
In route to Cumberland from Pittsburgh there are a number of small, old coal mining villages through which the trail passes many of which have small playgrounds with swings, slides, etc. Most have some form of covered pavilions with benches that provide some shelter if rain is encountered. There are not as many opportunities nor are they in the same proximity to the trail itself along the C&O south of Cumberland.
The children may be most infatuated by the trains that parallel the trail over much of its distance. Unfortunately they run at night as well. :-)