Dock leaves are the best but I found standing knee deep in ice cold spring water worked very well when I fell into a patch up the dingle when I was a child. There weren't enough dock leaves to cover even two short legs.

It actually depends how you grab them. The stings lie slightly in one direction, so you have to come up with the flow of them rather than against them. The problem with the theory is that nettles tends to be big and branch out a bit, so you might protect your palm, but something will get the back of your hand.

And they do sting through clothing. Try walking in trousers through a nettle patch and you'll find out.

Ouch!
By the way, if you want an interesting use for your nettles, they can be used for wool dying. Must find some to use at some point...