Is this your first time at Poncho's. If it is you will enjoy your stay. It is a nice place.
The city of Ludington has "Friday Night Live" parties downtown on several Fridays during the summer. There will be one on the 17th and 24th. The kids would enjoy them. They close off the main street through downtown and have lots of activities, food, entertainment, etc.
There is a nice large playground at the Waterfront Park in downtown Ludington. Pack a picnic lunch (or pick up pizza on the way) and eat it on the tables at the park and watch the boat traffic.
The car ferry "Badger" docks there also and the kids (and parents) would enjoy seeing it depart or arrive. Check the schedule but I think it arrives back from Wisconsin around 6:30 pm and departs around 8:30 pm. It also has an A.M. arrival and departure.
Thursday the 23rd there will be a sunset bonfire at Stearns Park along the Lake Michigan beach. The beach at Stearns Park is very nice and a walk out on the pier is always fun. The House of Flavors ice cream restaurant downtown is within walking distance of the beach/park.
The beach and hiking at Ludington State Park is great also. If you have bikes the state park has a nice paved trail in the park.
If you're a fan of The Eagles (tribute band) music there is a free concert at the band shell at Waterfront Park on the 25th. One of only two such concerts during the summer, they usually draw a good crowd and it's a fun time.
Be sure to pick up some locally grown sweet corn while in the area.
We have gone up there to the state park for a stay every summer for decades.
Enjoy your stay.