I use a Bushnell Yardage Pro 600. I take it hunting with me.
When my husband and I hang our stands one of use will sit the the stand and call out the shot areas and shooting lanes to the other on the ground and the ground person will then do a little trimming . The One of us in the stand will then range the shots and the one on the ground will mark the shot distances, I prefer to use reflective tacks to mark the distance to certain trees( if its 30 yards I use 3 tacks , 20 yards 2 tacks etc,to mark it). When we dont have time to prerange an area I will upon climbing into my stand take readings in the areas where I have shots around me. I shoot a weekly in indoor league and four different 3D shoots a month , but still find yardage estimation to be my biggest hurdle thus comes into play the range finder. I find my Rangefinder to be a very valuable hunting tool.