The measurements are fairly standard across the different games:
For 15mm scale or smaller models, use the following lengths: Short 50mm; Medium 80mm; Long 120mm
For larger scale models, use the following lengths: Short 75mm; Medium 120mm; Long 180mm
However, when it came to Songs of Shadows and Dust, I found that I had a slight problem. I have always suffered from short articulated stumps where your common man has fingers. Don't get me wrong, they look like figers and have nails and everything else you'd expect, but they were never destined to do graceful things, like play the piano, or be a hand model for Nivea's latest skin care range. Anyway, narrow alleyways between model buildings can be slightly awkward when you have dumpy fingers trying to use measuring sticks and move models.
Early in playtesting fellow Wee Gamer, JB, made an enlightened suggestion which has proved highly successful. I attached my existing copper rod measuring sticks to little handles cut from balsa wood so that they form a T shape. I can now lower the measuring sticks into the tightest of spaces by the handles, thereby keeping my fingers out of the way.