Final approach speeds are definitely lower than high-power T/O speeds, although it can vary. MD
-11s are going quite fast even when they touch down, while A320s seem to be going quite slowly by comparison (the MD
-11 has a very high approach speed in real life, so this isn't just perception).
It also depends on where you are shooting.
At Seatac, you can't really get a rotation shot from anywhere except in the terminal (or possibly air-to-ground), so if you are photographing takeoffs there, the planes will be stowing the gear (or about to be) by the time you see them come into view (the entire airport is on a plateau about 15 meters above all the surrounding roads). That's a bigger challenge than watching them slowly close in on your position at a slower rate of speed.