In the immediate area....
Capt. Jacks is good for dinner and has good pizza (carry out avail.) at a decent price
Lakeview is more of a lunch place but is also open for dinner and is a bar at night
Driftwood Summer shop has ice cream and local merchandise (t-shirts ect.) and video games
If you drive into Dowagiac (10 min.) Zekes has ok food and Woodfire is very good but plan on spending some cash if you take all the kids
The store is Myers, pretty much the only option but it gets the job done.
For breakfast you have to go The Wright Place, when my friends come to visit they insist on going there every morning, great food in my opinion.
At night for the teens they are gonna want to have a bonfire or or go out on the boats, thats about all there is to do for our age group, but if your with the right people it can be a lot of fun.
I am staying there all summer (Big Crooked Lake) so let me know if theres anything else I can help with.