I'd go with what bagginsbill is suggesting.
Wherever you can, for brick and similar repeating patterns you want to go with a procedural shader. Especially a well made one which allows for some realistic variation. I haven't seen a shader from bagginsbill that wasn't well made :)

If you are going to use a tileble brick image, find or make onw with very little variation across the image. This will minimize the unrealistic part of the repeating look. Even with an image based shader, you can always throw on there a little bit of procedural noise that will vary bump or coloring. If the image map is too fuzzy, I would throw in a procedural sharpen node (I'm not sure if Poser has a sharpen node - I'm going on general principle and using half a dozzen different apps)

If you have any of stonemason's props, I'd highly recommend examining how is peces are UV mapped, and how his shaders are put together.

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