How and where to hang pictures

[pinktransit]

I have 3 photographs, framed, with frame and mount they're about A3 size.
I want to put them up on the wall above my sofa, but have no idea of how best to arrange them. They are all landscape orientation.
I don't think that 3 in a row will work well, but neither will one above the other.
So diagonally? Randomly put wherever I happen to put a nail in?
They are of an elephant, a pair of hornbills and an agama lizard.

Is there a website or anything that makes suggestions? I used to have one big picture hanging there - I've never actually tried to make a group setting sort of thing before.
Suggestions please - otherwise I can see myself giving up, and just rehanging my original picture: this is a photograph of my 2 daughters, taken about 9 years ago. They won't be happy if I put it back up!

Not randomly if they are a set (which it sounds as if they are). Horizontal sounds fine to me.

They are sort of a set, but not completely matching. Different scales, lighting, size - so one really close up, one less so, and one from more of a distance. They don't exactly match.
I think horizontal might work if I can get the spacing right. They are an awkward size, so to space them nicely they won't fit centrally over the sofa that's against that wall.

You might be better off adding another if you can find one ( ie one above the other twice ) if you have the wall space - ie from top of sofa to bottom of first pic (X )mm (300mm for pic ) then smaller gap of 150mm to bottom of next pic (300 for pic ) then (X) left to the ceiling ! Place them 75m to the left of centre and 75mm to the right of centre ( so middle gap is 150mm too ! ) to work out (X) take the height from top of sofa to ceiling - then subtract 300+300+ 150 = 750 and divide by two !

Alternatively look on here for tips www.sasinteriors.net/2011/07/creating-a-photo-wall-display/