Have you tried the transport museum in Alford? I mind loving that place when I was a kid.

Not in the area, but take the loon to the National Museum in Edinburgh - you'll both absolutely love it. I went to school just outside Edinburgh and there was a trip there every year and I've always loved it there. Had my 3 & 5 year olds there in December for the first time and we were back at the beginning of February as they went on about it so much.

A wee trip on the train to Dundee to see Discovery and the science museum was another winner. Both brilliant places for the kids.