I prefer trees w/adecent amount of cover at 10-15 ft up, but as we all knowit doesn't always happen in the right place. If need be I'll go higher until Ican get to the overstory to help break up my outline. To a point at least. I hate sharp downward angles, especially if my body is falling thru it.

My favorite is a big ole gnarly cedar tree nestled against a straight trunked hardwood for my stand. Now that's concealment!