Visualizing multiple continuously-varying attributes across a region of space is a complex problem. We have recently introduced a visualization scheme based on Attribute Blocks, a regular array of cells, each of which is assigned an attribute. The Attribute Block array can be dynamically sized and tiled across a field of view to allow an arbitrary number of attributes to be visualized at once on a single display. The technique imposes no limits on the number of attributes that can be visualized at once, however human perceptual limitations clearly do. In this paper we briefly discuss related literature, review the Attribute Block method, and then discuss ongoing work whose goal it is to develop strategies for designing Attribute Block displays which maximize users' abilities to visualize how multiple attributes vary across a region of interest.