I think with almost all campaigns where your playing all the same race in a multi-racial world, that races society and how that race is viewed by others will be a strong concept throughout.
Beyond that, it depends on what these Elves are like.
My first 3E campaign was all elves. I wanted to run 2E's Night Below and decided to set it in the south of Faerun near the nation of Dambrath. The wild elves of the Forest of Amtar seemed to be a good source of PCs so the players duly decided to make an all wild elf party.
I included some events based on the deities that the wild elves follow and also designed a specific prestige class based around the wolf as a totem animal. All in all, quite satisfying but I wish I had spent more time on developing some of the cultural aspects (but difficult as one of the players is notorious for giving hints that he wants to play one way and then going in another direction entirely... and taking the rest of the players with him).
With a party that has no regular light people, I would take great advantage of low light vision. Have a lot of the fights be in moonlight,and let the party get the drop on enemies who aren't as killed fighting in such conditions.
Have the players make use of the fact that they can have known each other for decades. An elf hits adulthood when he's 110 years old. Have them know absolutely everything about their home town's environs due to the amount of time spent there.
Let decades go by. Really, there's no rush. Mention how some human upstart empire was founded, expanded, built some castles, and then was wiped out by demons; all while the PCs were taking holiday in the Feywild.