One that I've seen commonly suggested, primarily because of it's ease is to run between Boreal Station and the Eye of the North outpost. I think there's four possible chests that can spawn here.
The first section only has stationary Wurms that only have melee attacks, then there's a few Avalanches. There's not usually any chests beyond the Avalanches so once you reach them just map back to Boreal and start again.
Another option for obtaining golds is to run all of the Treasures in Nightfall, see
http://wiki.guildwars.com/wiki/Treasure for more details. As this doesn't require lockpicks though it won't add to your Treasure Hunter Title, but it provides a decent amount of money to buy more lockpicks. Just take note that you can only do this roughly once a month.
Hopefully that helps.