On the Innova's transmission, D3 is enough for baguio... you can use 2 for steep parking ramps, but very few roads in Baguio are that steep.

RE: 2 on a parking ramp... important so that you don't have to press too hard on the throttle to go up... when the ramp is wet, you don't want to use too much gas on the climb, as all this will do is spin the wheels. Especially if the dork in front of you has stopped at the ramp exit, forcing you to stop mid-slope.