Like Brent, I use 63 knots for the Max Glide speed and 600 fpm for the Rate of Descent. The green Glide Circle is kind of neat and potentially useful (including its consideration of the winds aloft on glide performance). However, keep in mind that the SV algorithm bases the size of the glide circle on the distance between your current GPS cruising altitude and the elevation of the surface directly under the plane. As a result, there are many potential situations where your glide performance could be significantly greater or less than that depicted by the green circle. As always, consider the Glide Circle as but one bit of input to your decision-making process.