Focus with a set aperture

Having decided to find a subject other than the ubiquitous row of cars I tried a couple of scenes.  The first attempt was to place 3 numbered marker poles along a lane but I found this did not illustrate the effect to my satisfaction.  Attempt 2 was a scene I noticed whilst out walking, a boardwalk through a wood which had good depth and had coach bolts in the handrail thus providing good reference points.

DSC_5177 - Shot 1

For the first picture I focussed on the near upright post on the left. Shot taken with 28-70mm lens at 31mm, ISO 200, 1/250 sec at f2.8.

DSC_5178 - Shot 2

Second picture I focussed on the next post along on the left. Shot taken with 28-70mm lens at 31mm, ISO 200, 1/250 sec at f2.8.

DSC_5179 - Shot 3

In the final picture I focussed on the third upright on the left.  Shot taken with 28-70mm lens at 31mm, ISO 200, 1/125 sec at f2.8.

The first photograph draws the eye to the nearest uprights as they are in sharp focus but in this scene I feel my brain is being confused.  The boardwalk draws me into the picture yet so much is out of focus I find it very uncomfortable to look at.  In the second shot there is more of a balance between the foreground and background but still I am drawn to what is further along the boardwalk; I find this easier to look at than the first.  In the final shot my curiosity is more satisfied as I can make out more of the background detail.  I favour picture 3 as I feel the scene is all about what there may be deeper in the wood and the foreground, whilst giving context, is not as important and, as such, not where I want the focus to be; certainly my brain seems happier computing this final image.