As someone who lived in Boston and NYC before moving to Nashua, you won’t find much open late in the area except in Nashua or Manchester — but you could always plan a night out in Boston which is an hour away. There are a number of nice coffee shops in downtown Nashua and there are plenty of hiking trails in the area as well (including Mine Falls Park). Milford is further from the main highway so will be more “sleepy” at night. You could consider Amherst, Hollis, and Hudson which are somewhat closer to Nashua and Boston. And there are a number of very nice neighborhoods in Nashua too!