We switched to 20lb BBQ exchange tanks in our 5th wheel when the 30's expired. When traveling it was not always easy to find propane refill stations. But every gas station, Home Depot, Corner stores, Hardware stores all carry exchange BBQ tanks. Even a large number of campgrounds are now carrying exchange tanks because the regulations for operating a refill station area are very restrictive. When a tank runs out it is very easy to put it in the car/truck/SUV on your daily site seeing, grocery or Walmart trips...
Convienence vs Quanity: The cost is easier to take and is spread out on trips, so if your not using it why pay for storing it for long periods then find out your tank expired. The exchange tanks don't expire.. and on average equal in cost.
B.