Liftouts are handy, but difficult to keep aligned if its constantly in use. The rail ends tend to get damaged and misaligned over time. They also bring a bit of danger to the trains because no matter how careful you are, someone will forget to replace the bridge, or someone will think the bridge is removed and walk right into it.
Duckunders often sound like a bother, but people duck down more often during the course of a day than they think. I considered a liftout once, but then remembered that any time I drop a pencil I have to duck, anytime I get into a car I have to duck, and that I didn't really jump into and out of the center of the layout that often, so a liftout was really just a needless project and a spot prone to failure. I suggest a duckunder, as high up as you can make it and with minimal benchwork thickness beneath it. Unless of course you have severe back troubles. Some people I know also use a rolling desk chair which should bring the height of your head down to about 3 1/2 feet if you bend your head down slightly.