You might want to hold off on the Feywoods... Yeah the enemies are level 30ish but they have a wonderful time swarming you and trying to tackle 10 of the Tomato monsters with three party members with the same level is still going to be a challenge. I'd wait since you'll eventually be going there anyway.

As for the Mines that the Jahara mentions... yeah, ANGRYWOLF is right. You don't want to go there. That's not a friendly place. He'll give you the key to access the rest of the Henne Mines once you obtain 8 or 10 of the 13 Espers.

If you are looking for new uncharted lands, I'd go to Balfoheim since its a bit of a detour on your way to Archades but you can get access to some really good gear there. You could also sneak into the Necrohol of Nabudis at this point and get some levels. You'll need to go here if you want to get Chaos later.

Once again, I'd recommend taking down the Espers. Adrammelech is probably useless now but Zeromus and Exodus will definetly be helpful to you at this point. Cuchulain and Zalera are also pretty nifty and have decent usability times at this point in the game as well.

Really, the trip to Archades is one of the larger parts of the game that finally lets you really explore the world. Have you tried traveling on one of the commercial airships yet? Have you visited the tribe in the Giza Plains? How about Nabradia? There are tons of little fun side-quests that should be available at this time as well.