Thank you to all those who replied. Your information gave some food for thought.
Here is some info in response to questions asked in response to my original post.
The puppies appear to be well socialized and we spent around two hours at the breeder's place talking about the puppies routine, observing the puppies, their interactions with each other and the mature dogs in the house. With all their running around I almost expected to see them at some point running on the walls or on the ceiling. :D
We were unanimous in our decision of which puppy we take (the one that fell asleep on my lap after running out of puff).
However, after we came back home we had quite a few long discussions about potential impact for both the dog and our household if such an energetic and intelligent dog becomes bored during daytime when all family members are at school/work.
Another issue is that the 'owner' of the puppy is our younger child. With her tendency to be a bit possessive and controlling about her things (we keep hearing at regular intervals about HER puppy) we thought that we needed some means to address that. So after considering all implications we could think of having second dog in the family we decided that it would be beneficial for both the dogs and for the human members of the family.
Now I'm thinking if getting two puppies was really such a good idea and whether by doing it we're going to get more issues than we thought we would resolve.