In some ways, I have had similar experiences as the original poster. I've been super excited to have the day off, have extra spending money, and make a long trek to a fabric store, only to hunt and hunt and hunt for something to buy. I chalked it up (mostly) to being in a quilting slump. But I am also a quilter that does not have young children in my immediate circle of family and friends and thus I pass by on all the kiddie stuff.
As for the inspiration part, I have found that if I flip through an older magazine, I can see a pattern that was done in calicoes that I know I can make look more timely by using my own stash. Scrappy quilts become more interesting to me.
Here is an example of something that motivated me. The pattern, called Pulsar, was published in a magazine 18 years ago. I used up a good amount of leftover scrap stash for it and then only had to hunt for the dark blue border fabric.