Trying to understand decoherence... how would macroscopic objects behave without decoherence?

When we say we "observe" that an object has a particular quantum state, we do not typically imply that we do so with a single measurement. Instead, we prepare the desired state many times, and make many measurements, so that we have a probability distribution of observed eigenstates. We can take the probabilities we get from our series of measurements and convert them, up to an overall phase, into coefficients in the original state wavefunction.

A question such as "What would we see if decoherence wasn't happening?" is moot, because seeing an object requires that photons from the environment constantly interact with that object, which cause decoherence.