Really? Of all the times that i came out to people, being right to the point has worked the best. there is no gray area as to what is being discussed. It lets the person have the initial "what?!?" moment and gave me the chance the then explain in response to their question. It has been my experience that by trying to spare feelings, the messages get mixed and nothing productive come from the discussion at all.
Could it also be said that by not being completely honest right up front is also being insensitive? It is merely deceiving them into thinking they will be ok with the idea when in fact they don't know the whole truth. To me, that would be insensitive.
Just for the record, my ex-wife (yes, ex) and I are still on speaking terms, my ex-girlfriend no longer talks to me (the whole deception and trust issue ruined this relationship), my aunt and uncle have crossed me off their Christmas list, and everyone else in my life has come to accept me for who I am. Regardless of how we come out and what we say, some people will not be able reconcile the idea of changing genders or the intense sense of mistrust and deception. With the few negative things that have happened I have had hundreds more that were positive. Even the negatives I chalk up as learning experiences so they still serve a purpose.
When it come down to the best way to come out, there is no best way. We can only discuss what we are ready to admit to the rest of the world. As long as you stay true to yourself you will do just fine.