Shape-shifting! That way I could do a number of cool things.
a) By changing myself on genetic level I may be able to make myself into whatever sex (or sexual orientation I want (hurray for experiential empathy))
b) I could change to a younger body of myself, even going so far as to shape-shift my useless memories out to avoid memory overload, or change my mind to a new one but with all my important memories, tendencies, etc (so my automatic muscular response section wouldn't decay over hundreds of years)
c)I could finally experience what it's like to be an animal (obviously using my ability to retain my humanity in a 'experiences wolf-i-ness, can exert absolute control over body and ability, yet does not impede upon the wolf instincts unless it wants to)
d) change into something that excretes a virus that either gives someone else my ability or changes them to whatever I wanted the virus to change them to)
So yeah, it gives the good kind of immortality where you aren't forced to live forever, you can choose your age and what-not, you don't have to abandon the people you love and you don't get the decaying mental or physical state that would occur from prolonged periods of life. Also, wolves.