There's a job I really want. How can I write a great cover letter?

There’s an opening for an assistant manager of a small gourmet market. I have experience as an assistant manager and I love this market. They are a local chain (maybe 5–10 locations) and they are partnered with another local business who supplies their coffee. They invented a type of cookie that is one of the few foods indigenous to my area, and they always have creative, colorful seasonal displays. This is basically a retail job because all the food gets delivered; the only thing that gets prepared there is the coffee.

When I was an assistant manager I was in charge of about 10–15 people, total or two or three people per shift. It would most likely be about the same at the gourmet place; they never seem to have more than two or three people on staff at once. Other than that, I opened and closed the store, did merchandising and window displays, trained the staff, wrote up daily totals, did banking for the store, tracked inventory levels, entered new shipments into our system, made a new filing system, worked to reduce shrink (stealing), and did some buying. I feel “meh” about a lot of the jobs I apply for, but I’m qualified for this one and I’d be genuinely excited to work there. My resume is great but I have trouble striking the right tone in cover letters. I know this is TL;DR, and I’d sooo not asking you guys to write the letter for me. I’d just like some helpful advice. :)