|When I can't quite visualize how a design element or type of fabric will look, I use the search feature on the on-line sites that sell RTW to get examples. Of course this only works if they've used the term in describing the item, but give it a try.
One site I use often is bluefly.com because they sell a lot of women's clothing that is quite varied in style and, most importantly, they have a search box. An example of how I used this method was when I wanted to compare how plaid looked on garments when the plaid was on the diagonal vs. horizontal/vertical. I simply typed in "plaid" and browsed their inventory. Today I suggested this tip to someone on the boards who was looking for a pattern to use for polka dot fabric. I typed in "polka dot" and quickly saw lots of examples, so I hope this tip will help her visualize a pattern she could use.
Many "brick and mortar" stores have on-line sites, so even if you could never afford to shop in the stores, you can still browse their inventory. Go check out www.saksfifthavenue.com, www.neimanmarcus.com, www.bergdorfgoodman.com/, etc. and search for design ideas!