In this work, we study quantized beamforming in wireless amplify-and-forward relay networks. We design the quantizer for the feedback information specifically to optimize the bit error rate performance of the system. First, we focus on networks with a single transmitter receiver pair. For such networks, we analytically show that a simple feedback scheme based on relay selection can achieve full diversity. We also find an upper bound on the average signal-to-noise ratio (SNR) loss. Using this result, we demonstrate that both the average SNR loss and the capacity loss decay at least exponentially with the number of feedback bits. We observe that our designs can achieve both full diversity as well as high array gain with only a moderate number of feedback bits. Then, we consider relay-interference networks with multiple-transmitter receiver pairs. Two different quantization schemes are considered. Using a global quantizer structure, we show that the relay selection scheme can achieve full diversity in this network model as well. We also design a local quantization scheme with distributed quantizer encoders, one at each receiver. We show that, with only a few feedback bits, high diversity gains can be obtained with the local quantizer structure as well. Simulations are also provided, confirming our analytical results. We observe that our designs guarantee an equal high diversity gain for each transmitter-receiver pair.