I do that all the time, its like second nature now.
I drive only city really, so i just put it in 3rd and leave it there, top speed I hit is like 50 mph.
Here is the good news, your car is newer than mosts, so your 4th gear shaft is WAY better than the 97-02 cars, in 03 then switched the 4th gear to a hardend metal, so it wont strip the gear anymore.
So putting it in 3rd will never hurt the tranny when going those speeds.
If you're doing 50 or faster i'd leave it in D.
if you're doing say 45 or less, 3 is fine.
It all depends on how often you like to kickdown and get some power. (not that you have much)