Kind of depends on the map ... I don't mind sitting way off and doing bullet drop estimations, picking off people ... but I like to be more in-your-face. I get too bored otherwise. I have a sniper round that I'll add here soon where I went 25-4 (?) on Flood Zone sitting right near the middle flag. On Rogue Transmission, I'll sit on the hill behind the middle flag (attack chopper spawn) which usually attracts a lot of infantry attention.
Sniping is obviously not my favorite thing though. I have a difficult time justifying my efforts as beneficial to the team. Not to say sniping isn't helpful, just that I don't know how to quantify it. I'd much rather be taking objectives and killing vehicles.