Two small paintings the same size; one larger painting: it would seem that the obvious placement would be to have the big one in the middle and the other two evenly spaced either side of it. That is not, however, how my wife saw it. She wanted to experiment with other placements, to see if any looked better.
Now to be fair, my wife did realise it would be unkind to make me stand there holding the paintings up for a couple of hours while she and our younger daughter debated where it should go, so she suggested we did it on the computer. That would have meant my computer, and it would also have meant I wouldn't have been able to use it while they were deciding. I therefore took a couple of photos of the wall with the paintings on and off, printed the one of the empty wall onto A4 paper, and cut out little card-backed scale models of the paintings from the other photo. This meant my wife and daughter could move the paintings around in replica.
This actually made it a lot less time-consuming, because they could play around with it over lunch. Here's what they finally decided on:
I think they want me to hammer some nails in the wall now, but I'm holding out for later on when I don't have to breathe vinegar fumes.