I have hosted multiple family events at the Lake Shore Village Resort: several children's birthday parties and a family reunion. The Club House allows for convenient large gatherings. The indoor pool is a great resource for winter months or if you get rain on your party date. The Manchester NH Airport is fairly close by for any travelers that have to fly in. In addition, cabins are available for weekend or weeklong stays for guests.
My family reunion was very successful. People raved about the amenities and the setting. For me, it was the easiest and simplest reunion I have ever hosted. I didn't have to clean my house before or after. The Club House served a deli platter on the beach and put several picnic tables together. I'd highly recommend this location for parties, reunions, or group vacations.