Traditionally, that is to say before piezo sensors became available to the masses, they were conditioned with what are known as charge amplifiers. Piezoelectric transducers are capacitive in nature, therefore the term, charge amplifier. A charge amplifier can be simplified to an op-amp with a capacitor instead of a resistor in the feedback loop.
The critical property of a charge amplifier is its time constant. Since piezo devices are electrically capacitive, they are a dynamic device and if you want to be able to maintain a "DC" output for a certain time, you must use a charge amplifier with a longer time constant. Obviously, the trade-off for better DC response is a reduction in bandwidth, but usually a compromise that satisfies the needs can be made.
So, long story short, depending on how you want to use a piezo sensor, it might make sense to condition it with a charge amplifier. For example, if you want to use it to measure something that is slowly changing you would use a longer time constant than for something that changes rapidly. Simply stated, the larger the feedback capacitor, the longer the time constant.
Maybe TMI, but I thought it appropriate to mention, at least. 