Things I can think of for now are:
In Glasgow:
Transport museum (free)
Art Galleries (free)
Transport museum (free)
Burrell Collection/Pollock country park (free)
Botanic gardens/Kelvingrove park (free)
House for An Art Lover (free I think!)
Peoples Palace/Glasgow Green (free)
GOMA (free)
Snowzone at Braehead is good as well for trying out snowboarding. dry slope skiing etc
Gambado softplay at Braehead
Wonderworld softplay in Kinning Park is excellent - it's massive!!
The Glasgow Science Centre - brilliant day out
Waverley boat excursion (might be a bit cold for that!)
There's free go karting tracks with karts, bikes, scooters etc down at Glasgow Green
Outside Glasgow:
Heads of Ayr family park (brilliant)
The Time Capsule (Ice skating/swimming)
M&D's theme park
Strathclyde park
Mugdock park
Chatelherault country park
Palace Rigg country park (with small animals to feed)
Kelburn Castle is amazing! Loads to do for kiddies
Balloch Castle country park
The Bubbles Factory (Carluke)
The Falkirk Wheel
Stirling Mystery Trail
Blair Drummond Safari Park
Eglington Country park (animals and indoor parts)
Go Ape (Aberfoyle)
Magnum Centre (Irvine)
I know not all are in Dumbarton/Loch Lomond/Balloch but some of them are worth a short drive!
Could probably think of loads more - I'll come back