There are loads of things you will already have planned, but here are a selection of outings you might not have considered that might be interesting. Troon / Prestwick / Ayr are all along the west coast near the house, and worth visiting
If you going to visit Glasgow for the day, you could always pop in to this mini golf course, which is in the centre
There is also a good one in Braehead, which is a large shopping centre outside of Glasgow
Pollok House is in the same grounds as the Burrell collection, so worth combining in one trip
Millport is a small island off the West coast of Scotland, where you can get a ferry to from Largs (a seaside town on the West coast, about 35 minutes away - also worth a visit)
You can hire bikes and cycle around the island (about 10 miles / 15 kilometers). It is best (and cheaper) to leave your car in Largs and just go on the ferry by foot. There is a bus on the other side that takes you to the town
Arran is a larger island - Scotland in miniature - which can be reached via ferry from Ardrossan. Ardrossan is about 25 minutes from our house and the ferry takes about an hour