I think measuring_stick is good. It's system neutral and it's not like we will always know what the units are on the stick anyway (plenty of fantasy series that might use their own units).
Off topic, since this isn't what the forums is for, but I can't really say I see a reason the US needs to embrace the metric system (at least as far as distance units go). If it's an issue of having a measurement system based on 10 intervals, then frankly I think a better unit could be developed than the meter. Personally I just can't see why anyone would think the meter is anything special when it's very definition (the distance light travels in a vacuum in 1/299,792,458 of a second) just makes it as arbitrary a distance as any other distance measurement unit.