Thanks everyone - definitely going to miss some names but:
There's Ross, Stuart, James, Callum and Fraser already in the immediate family (we're large and close, Euan is already the name of a more distant relative!)
Alasdair I quite like, but not sure if Ali is inevitable (probably a 50:50 split in the ones I know). I had dismissed Gregor as I don't like Greg, but the McGregor point is a good one I hadn't clocked! Alexander I think is inevitably an Alex, which I don't mind but I don't love. I prefer Robin to Robert, but DP isn't sure about Rob. Hamish I'm not keen on. Think everyone is right that Lachlan is just asking for disappointment in an English accent. Finlay/Finn I like but there's so many of them locally I'm not sure. Ivor makes me think of Ivor Cutler, which isn't necessarily a bad thing!
DP reminded me that Calvin was on our list, I think solely because DS found my Calvin and Hobbes books and declared he was Calvin. He could pull off Calvin to be fair.
So:
Euan and Angus
Euan and Innes
Euan and Fergus
Euan and Finlay
Euan and Robin
Euan and Calvin
Euan and Kester
Euan and Magnus (which I'm not quite ready to give up on)
I'm going to end up as someone who waits until the baby is born to decide, despite my firm belief that no baby actually suits a normal human name!