Must see in Maine?

Lubec is the easternmost spot in the US that you can drive to. Nice flag to add to your travel history. Be sure and visit the lighthouse.

Head up to the town of Lubec, then cross over to Campobello Island. The Roosevelt homestead is fascinating. The drive up the coast is beautiful and not crowded as many folks jam into Bar Harbor and go no farther north.

This precisely why we skipped Bar Harbor.

Bar Harbor-sailing, shopping, whale watching, restaurants
Schoodic Peninsula
Acadia
Desert of Maine
Freeport-LL Bean flagship store plus outlet shopping (if you are into that)
Ogunquit/Wells/York area-beautiful beaches (but cold water), water parks, Nubble Lighthouse
Kennebunkport-shops, restaurants, Bush compound
Portland-sailing, shopping, whale watching, restaurants
Baxter State Park-canoe, kayak, hike

Bar Harbor KOA-pricey but beautiful locations. Sites are cozy. Incredible sunsets, lobster banks, pancake breakfasts

Schoodic Peninsula just above Bar Harbor. Great NP campground (make reservations NOW). Much less expensive and less crowded than Acadia and Bar Harbor and,in my opinion,much more beautiful. Maine the way it should be. Visit Portland (park at north end of main drag-Commercial St?). Great walking town. Many shops and restaurants. Twin lights in Cape Elizabeth,Freeport,Kittery. Basically,all of Maine.

Maybe look into the Camden,Rockland area of ME, might be worth a couple of days. State rd 1 about 1 hr south of Acadia. Camden Hills State Park lots of shopping and outdoor activities in the area

Old Orchard Beach in southern ME your teens will like the beach, arcades and Amusement Parks. Tons of campgrounds in the area

Mike

Here is one that will be remembered:
Eartha

And here is another MUST(LOL) see :
Great desert of Maine

Baah Harbor. Take plenty of cash, you'll need it.

You could also do a Google search for Maine tourism.

Stop in Freeport ME. It's a nice town.
Visit L.L. Bean and other shops. I believe you can still overnight in the public parking lot on Depot St..