Hi, my family and I are all from Massachusetts but we have a vacation home in Bethel. While the summer doesn't have the wide array of things to do that the winter does, or the scenery of the autumn, it's not a bad time to go to Bethel. There's enough to keep everyone entertained.
The Bethel Inn and Country Club is a nice little complex. It's rustic and cute. There is a decent restaurant right on site, but in my opinion the best restaurant in town is down the street called the Sudbury Inn. Downtstairs from the Inn there is a pub called "Suds Pub" with live music and an all round enjoyable atmosphere. The town itself is cute and there are some nice little shops to take in while visiting.
The children will really enjoy the Big Adventure Center which has mini-golf, water slides, lazer tag, indoor rock climbing, etc (
BIG Adventure Center ). You can also rent ATVs from various outfitters and take tours of the woods that way... it's a lot of fun. Try canoing in Bethel too... it's an excelent way to spend an afternoon (
Bethel Outdoor Adventure & Campground - Route 2, Bethel Maine - 800 533-3607 ). There's plenty of golfing and hiking in the area as well.
Also, consider whitewater rafting on the kennebec river about 2.5 hours drive East of Bethel. Crab Apple Outfitters is one of the favorites (
Maine White Water Rafting - White Water Rafting in Maine ) and it's a great adventure for the whole family.
If you're going to see Mount Washington, the Cog Railway is an excellent experience. I'd also consider hiking it, or driving up on the Mount Washington Auto Road (
Mount Washington Auto Road ).
While in the Mt. Washington area, don't skip over North Conway. It's a great town with a lot to do. First, check out the Conway Scenic Railway (
Conway Scenic Railroad ). It's a fun train ride on gorgeous restored classic rail cars that give you a great and unique view of the White Mountains and beyond. Next, if you're kids like rides, check out Storyland:
Story Land . At age 11, your boys will be on the older end of the target demographic, but they'll still enjoy the rides and the park.
The Alpine Slide, near N. Conway on Attitash Mountain is a BLAST in the summer time. It's literally like a luge (minus the ice) on a sled you control down the mountain. They also have water slides on site. here's the website:
Attitash | Alpine Slide- The Best New Hampshire Skiing With NHs Most Powerful Snowmaking System (http://www.attitash.com/alpineslide.html - broken link) . Also look over the other activities on that page. There is downhill mountain biking, a pool, scenic chairlift rides, etc.
The zipline at Wildcat Mountain is fun too:
Fly Wildcat on the ZipRider- the area's newest attraction at Wildcat Mountain Ski Resort in Pinkham Notch New Hampshire
While in town, I recommend eating at Delany's Hole in the Wall on Main Street (
Delaney's Hole in the Wall - Homepage ). It's good pub food with home made root beer and cream soda as well as some pretty good sushi. There are a ton of other restaurants in town along the main street and rail station area so check them out too.
Shopping in N. Conway is fun too. They have a bunch of shops on the Main street in the center of town (many local crafts and clothes, etc... even a huge candy shop). There's also a factory outlet village in N. Conway as well (
Settlers' Green Outlet Village ).
More info on N. Conway and the area here:
New Hampshire Chamber of Commerce | North Conway Lodging Jackson NH Village Vacation Tourism Mt. Washington Valley
Seeing Portland and Freeport is fun too. Freeport has the outlets and LL Bean... check out the "adventure schools" at LL Bean (
L.L.Bean: Outdoor Discovery Schools ).
Portland has the Old Port area and the "Arts District" which really comprise about 90% of downtown Portland which is a small, walkable, compact area. If you want a cool dining experience but don't care TOO much about the quality of food, check out Dimillo's Floating Restaurant (
DiMillo's Floating Restaurant - Seafood, Beef & Italian Fare on the Portland Waterfront ). It's an old ferry boat which has been converted to a restaurant on Portland's harbor. It offers nice views but is a bit touristy for my liking and the food is mediocre. Fore Street and Hugo's are good bets to see the best of Portland's food scene.
You may want to take the ferry out to Peaks Island or Great Diamond Island for a few hours as even the ride itself is pretty.
For more entertainment, head about 1/2 hour south of Portland to Old Orchard Beach (
Old Orchard Beach Maine Vacation, Oceanfront, Lodging, Dining, Family, Resorts ). This is more of your prototypical crowded beach town with a pier, some rides in the town center and a big 'ol beach. Funtown USA in Saco is a fun little amusement park as well (
Funtown Splashtown USA ).
To see some more unique parts of the coast, I'd suggest heading to Ft. William State Park in Cape Elizabeth and checking out the old fort and the Portland Head Lighthouse (
Welcome to Portland Head Light ).
A little closer to Bethel you have Naples and the Lakes region. This area is beautiful. Naples is a nice little town with lots of activities. You can take a cruise on the Songo River Queen (an old steamboat) and really take in some of the scenery (
The Songo River Queen II - Maine boat cruises for groups, weddings and functions ). There are also seaplane rides out of Naples as well.
This is just a start, but I hope you find some interesting ideas and somewhere to begin. Enjoy your trip!