I've used Garden Grocer two or three times, great service.
When I'm East of World Drive, I usually go to the Winn Dixie on Apopka Vineland; head out the DTD exit, and turn left (north) on 535. It will be on your right hand side. Prices are a bit higher than Publix, but I find the Publixes over on that side to be harder to get to. I'm lazy on vacation....
When I'm West of World Drive, I usually go to the Orange Lake Publix off of US-192. There is a newish Super Target over there too. You can take Sherberth road from Osceola, over by AKL, to catch 192 very close to the Publix.
For MK-area, I'm guessing the back way out to Winn Dixie is faster, but probably not by much.
I've read a lot about Goodings in Crossroads, and this is probably the most convenient to nearly anywhere on Disney property. But, I found it to be dingy, dirty, and not well-kept (water stains on the ceiling and carpet, etc.); surprising given its reputation as a pricey gourmet store. I walked in, looked around a few minutes, and walked right back out.