plans to free range!

So currently our chickens are not free range, they live within our inside and outside coop's, which are enclosed.  We have been thinking that it would be nice for the ladies to do some free ranging in the warmer months, allowing them to find all the tasty treats (seeds, bugs, etc) throughout the yard.  So we've started looking into a couple ideas to allow a few ladies at a time to free range safely from time to time.  It is not safe to allow our ladies to free range as we have a large coyote and hawk population in our area and our neighbour is quite fond of toxic chemicals on his lawn, so we don't want them consuming that.
Here are a couple photos of what we're talking about building (well Michael building anyway...not me...)  Final plans yet to be decided...