I would rate picking out fabrics/colors for my projects as the favorite part of quilting. Yes, I love it!
I normally have a color or a theme that I want for a certain quilt/pattern. Sometimes, I have to go to more than one shop, check online or whatever to find THE fabric that best goes for the specific project. Once I've decided on my focus fabric, I take the whole yardage, yes, not a swatch, the whole thing to the quilt shop and lay it on their table, then start hording bolts that I think will match my focus fabric. At the table (or sometimes the floor), I l unfold enough of the bolts to overlap my focus fabric, I arrange them all so the fold is facing me but enough of the fabric is showing, and I stand back. This is the easiest way for me to decide on what matches, what stands out and what blends. Again, depending on what I want from the quilt, I pick the fabrics accordingly.
If I have fabrics I am using or think I am using from my stash, I take them along too. Always have to look at the big picture and I am constantly amazed at how well colors, that I wouldn't think would match, work well together.