I am in a very similar situation. I have a 16X24 outdoor pavillion already built up at our lake property so I will be following this thread. The uprights are steel with a metal roof. We have a mat that lays on the ground that keeps the weeds from growing and you can actually walk in there barefoot but I will be pouring a concrete slab. My stick burner occupies the six foot section in the rear so that leaves me a space of 16X16 to work with. I plan on building 36" walls and adding counter tops of a undecided material.
Don't need a built in gasser. The stick burner handles nearly everything that needs to be smoked or grilled. I am going with a 36" counter top griddle with a wind break built around it. The exterior of the walls will be metal siding that matches the post frame building in the background. Other than that the rest is pretty much a blank canvas. Like you Binford I have considered concrete counter tops but two things in life are guaranteed. Death and cracked concrete! My neighbor is doing something very similar and is using concrete counter tops so I'm going to see how his come out.
Perhaps we can bounce ideas off one another Binford. Here is a pic of what I'm starting with.
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