I agree....
I agree with most of the folks who say that the players may surprise you. As a player and a DM, I know that there are many times in the past when we have totally blown away the DM's assumptions of what might happen due to our tactics or methods. Other times, well, we've died.
One thing that I as a DM, and my party that I run understand, is that you can die in any encounter, especially if the dice are having a bad night. You can't let them believe 'the dm won't kill me because we're heroes' line, because even if you try to not kill them, sometimes it happens anyway. They are adventurers, adventurers don't have the most safe of occupations.
Hopefully your hints will help, but sometimes you have to just trust that the players will come up with something interesting that will work.