GO with your instinct and use the fabric that makes YOU happy, no matter how much the old nag in the Quilt Store tells you how wrong you are.
When the pattern is very involved and you have never done it before MAKE A TRIAL BLOCK. You can test the instructions, the measurements, and the manner of assembly.
For all involved patterns, make a detailed plan that you can check off each step. It helps me keep the work going and everything in line.