I agree with chaika -- if you put "please" first, it sounds as though there is an emergency and you are desperate:

Please, could you help me find a doctor?! My child has a very high fever!

Please, could someone answer my grammar question before Wednesday?! I'm preparing for an exam at school!

(Also notice that in both of these examples, there must be a comma after "please," and therefore a small pause when speaking.)

But if you aren't "desperate," then Could you please tell me whether... gives the sentence a more natural-sounding rhythm.