I decided I wanted to open carry sometimes, I was driving around while open carrying my M&P9 and decided I wanted to check out sporting goods at Walmart (no better way to waste a rainy Saturday). Thought I'd share my experience.
I know some Walmarts allow it, others don't. I have never seen 1 person in my city open carry... EVER, so I was slightly nervous of course. I called them up and asked to speak to a manager, I asked if they allowed open carry. He said "we don't have any signs posted, so yes we do". (wrote down his name in case I had any troubles) Spent a good 30 minutes in there looking at ammo/gun supplies/and bikes for me and the wife, other than a few small kids I don't think anyone even noticed (from what I could tell).
I used a Blackhawk OWB holster w/spare mag pouch (yes make fun of my Blackhawk if you must, but it's a good holster for cheap). My voice recorder fits perfectly in the spare mag pouch, so I turn it on before I go anywhere (just in case).
Overall a very good experience, I plan on open carrying more often, and finding which businesses do and do not allow it.