I grew up in Concord (pronounced “CON-kid,” never “conCORD,” that’s an airplane) and yes it has some great sightseeing - a full day’s worth between the Old North Bridge and the Manor overlooking it, Nathaniel Hawthornes’s house, Alcott House, Author’s ridge graveyard, Walden Pond and nearby Lexington attraction Minuteman National Park.
If you like the beach then Cape Cod is a delight and there is a long bike trail, I expect you can rent bikes to enjoy it, you can ride to beaches and views. With the first gay-friendly city, Provincetown (P-Town) at the end. You can take a ferry there from Boston.
On the North Shore near Gloucester (pronounced “glaw-stuh”) there is great off-the-boat seafood and the delightfully shallow Wingaersheek Beach which is great for frisbee at low tide due to the acres of flat sand. There used to be a clothing-optional beach (Singing Beach? The sands sing while you walk) also on the North Shore. North shore is anything north of Boston, but these two are both on Cape Ann, which is the next major land-knob north of Boston