Brenda gave you all kinds of good facts, so let me address your question from a slightly different perspective.
My short answer is: There are no significant advantages, or disadvantages, in living in a particular zip code unless you have school-age kids and want to drill down on the performance/satisfaction ratings of varous schools.
Zip 30359 is the City of East Ellijay, so you'll pay more in property taxes there than you will in un-incorporated Gilmer County. The same is true if you buy a home within the city limits of Ellijay, which is located entirely in 30540.
All of Ellijay and East Ellijay have county water and sewer services as so some parts of unicorporated GilmerCounty. County water will save on your homeowner's insurance, But, over time, the combination of water/sewer and insurance costs may well be less if you have a well.
The lesson here, I think, is that every buyer and every property is unique, so a more fully-informed answer to your question means knowing more about your hopes and concerns.
Zip 30540 encompasses virtually most of Gilmer county. There are two other zips -30536 and 30539 also in the same area. 30539 is E Ellijay, but our office is in E Ellijay in the Walmart/Lowe's shopping center and has a 30540 zip! From someone who lives and works here, the whole area is beautiful. It depends on what your goals are as far as living in the area.
Zip 30536 actually begins less than a mile from Hwy 515 on Yukon Rd near the new Ingles and stretches to the Dawson county line. The apples houses in the Cartecay area, new vineyards, new middle school and a high end subdivisions such as The Hemlocks, Greystone, and Falling Waters Club subdivisions are located within this zip.
Zip 30539 for E Ellijay is mainly along Hwy 515 or within a couple of miles. The rest of the county is zip 30540.
Gilmer county has many beautiful mountain views, lakes, trout streams and natural beauty.
There is more commercial development close to Hwy 515 where most of the city water and sewer was installed but again, many great developments are located in a ten to fifteen mile radius of Hwy 515 that have their own community water system or private water wells.
Of course, when you have commercial development, it attracts the masses with restaurants/fast food such as Longhorn's, Ruby Tuesdays, IHOP, Chick Fil A, etc. plus shopping but in our rural county, many people come here to get away from it all and like the privacy of moountain living. Infrastructure enhances values especially for commercial but not having it in mountain communities hasn't necessarily made them decline in value.
If you would like any additional info or links to the area, please let us know and we'll try to help.
Brenda & Don Regan
The Regan Team
Metro Brokers GMAC
"Come the Beautiful North Georgia Mountains - a piece of heaven on earth"