The Blue Hills are about 45 mins south, depending on where you’re coming from. I love going up to the White mountains in NH (Franconia, etc) but it’s usually still pretty snowy there (at least the higher peaks) until May and then pretty packed on the weekends throughout the summer. It’s 2.5-3 hours from Boston so I usually leave at like 4:30AM to make sure I get a parking spot at the trailhead.