Lay box question

[Kensfarm]

I am building an Ark or A-frame style chicken coop.

I have looked at so many different plans and taken bits that I liked from each one, but I have a question about the lay boxes for hens.

Here is a couple photos of what I have so far.

Not super fancy, but I made it much larger than most of the designs I have seen. Still not finished, need to head back to home depot soon as next paycheck comes in

It stands 6 feet tall and then length stretches 8 feet.
I wanted to make sure plenty of head room was available to the chickens and plenty of floor space if they had to stay locked in for a while.
I plan on letting them free range the back yard everyday, but if bad weather or we need to leave the house I wanted something big enough and secure enough for them to be comfortable.

Anyhow, I plan on making 2 lay boxes at each end of the upper level of the coop, that can be accessable via a hinged door. So the top level will be completely enclosed.
I don't know if I should actually make a "box" or "cube" with plywood that the hen can get into and be completely enclosed. Like this:

or
will a 2x4 frame that the hen can sit in and lay an egg be enough. Like this:

I would rather to the 2x4 frame, seems much easier for me. I want to make sure that the hens would like it though.
Throw all your opinions at me please, I take constructive criticism well.

 

[Captain Carrot]

either would work fine. Chickens like to lay somewhere quite and dark (not all of them). I like the look of the last photo though. Fill it with straw make a depression with your hand in the straw, and add a couple of clay/plastic/real eggs or golf balls inside and the hens will see it as a fantastic place to lay...it has to be right? someone already laid in there.

 

[Kensfarm]

Sounds good, is straw best? or can wood shavings be used?