We don't buy much propane for our coach, so I usually use campground sources for convenience, even though they are typically the highest priced.
In my experience the local LP retailers generally do not have easy access for large coaches, but often the large LP distributors do at their main location. If I'm not familiar with the area, I call and ask, or drive by in the car first to make sure. Sometimes it's a matter of time-of-day, i.e. when parking lot traffic is minimal. My local hardware store has fair access and a long hose, but the layout is such that I invariable get blocked in while getting a refill. For that reason, I don't go there with the coach anymore.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL