Saddle height

Sorry, to answer your actual question - the 109% method and the best way to measure absolute seat height across all your bikes - align the crank arm with your seat post so they form a continuous line and measure from the axle centre to the top of the seat. In reality it's impossible to measure the centre of the pedal axle, so measure 10mm above it then compensate at the top. Saddle flex will be an issue too, so keep an eye on that.

Lemonds is 89% from centre of bottom bracket to top of seat (but this assumes everyone is using the same length cranks!)

Double recommend Steve Hogg. Any formula will be wrong, it's just a start line. Used the Hogg 'hill climb' method. Seat went down about 15mm and the back pain tailed right off. Cleats went back 8mm and the ankle pain stopped. There's a lot in Hogg that looks extreme but what he is actually saying is be comfortable and efficient and keep asking questions about your position and your life. In the very least Hogg will make you stop thinking there is a 'formula' and will stop you listening to the utter BS that people just like me used to spout about position!

Steve Hogg is well worth a read on this subject.
http://www.stevehoggbikefitting.com/blog/2011/02/seat-height-how-hard-ca...

Up the seat tube works for me!