piezo's producing small signal and multiple drum triggers

I'm making an electronic drum set with piezo sensors. Currently I have two issues. First, the piezo's are producing relatively small signals. When printing the digital values on the serial monitor, the highest values are in the 30s (on a scale to 1023 of course). The sensors are in parallel to a 1Mohm resistor (I copied this from a few other piezo projects I found online).

The other problem is that I'm getting multiple triggers from a single drum hit. I'm assuming this is because the arduino samples the piezo signal multiple times after a single drum hit because the fall time of the sensor is slow relative to the arduino loop time. Is this accurate?

Any ideas on fixing these issues?

Thanks!

Well in general higher load resistor means higher signal - 1M is pretty high though - try removing it and just having 10k in series to limit current to the pin? You are biasing the other side of the piezo to midrail? If not try reversing the connections to the piezo element, the biggest spike will be the initial impact, that'll only go in one direction.