I've been giving more thought to which words I choose for articulation practice lately, by considering the frequency of use of the word in addition to the position and vocalic context.
Summer is a great time for me to get organized for the coming year....so, to start, I've created a "Frequently Used R Words" list sorted by initial, medial, final position and blends.
You can pick it up here.
It was a huge help to me when I was organizing my summer practice packets too! Click here if you still need to pick one up.