I'm pretty sure the OP is asking for what technique iFly users prefer to find distances/bearings in order to make a good position report to ATC, not how to verbalize a position report.
I generally use the distance ring like you described in your intial post, but if you're looking for other options I can think of two:
1) Tap and hold on an airport or navaid (or any arbitrary point on the map). When the circle of dots turns green (about a half second), let go. The top of the box that pops up will give you the distance to that point on the map, rounded to the nearest nm.
2) Touch the screen with two fingers, one on your ownship and one on the point you want to measure from. (Separate the taps by a few milliseconds, touching your ownship first and then your target point.) Hold for a second or so, then let go. A line will appear, anchored where your first finger touched and stretching to where your second finger touched, with a box in the middle showing distance and bearing to target. You can use one finger to grab either endpoint and move it around, and the line will persist through pan/zoom until you single-tap somewhere on the map background to dismiss it.
Actually, I'm not sure we're using the same distance circle, because you say, "To use the iFly distance circle requires some guesswork." If you're talking about the black compass circle that's always present around your ownship and changes in distance when you change zoom levels, then yes, that might require some guesswork if there's not a zoom level that plops that circle right on top of the point you want to reference yourself to.
But the feature I typically use is to touch the screen and drag. This will create a light-blue "dynamic distance ring" that goes through a crosshair at the center of the screen. You can then pan the map so that your target point either falls under the crosshairs or any other part of the blue arc, and you'll see a distance box attached to the arc so you know the exact distance to your target. No guesswork required.