When I quit my job of 2 years I didn't tell my boss. I was truly unhappy with the way things were being run and just wanted out! My co-workers knew, but only because they were all doing the same thing. In fact, we covered for each other when one of us had an interview. I even gave a peer recommendation to one of my friends.
I think hinting that you are leaving the company/job is really for people that are
extreamly valuable. Not to say that you aren't, but we all know how these things work. The more money you bring in, clients you attract, cases you win, or successful surgeries you perform the more they will fight to keep you. Even if you work in a 'supporting' type job (i.e. Administration) if you are damn good they will fight for you.
You have to ask yourself why you are leaving. Is it monetary, social, spiritual, or are you just plain unhappy? Is it the wrong job for you? If these things could be fixed would you still leave?
Also, ask if you are seen as disposable. If the company can do without you then it's better to keep quiet. But if you pull a lot of weight then you can make them squirm.
And if you have PTO, take it!