Well, you might (SPOILER)try going to Triangle Island and fighting the Intangir, though it's a heck of a battle. At least you can get the Rage for Gau later on. You also get 10 Magic Points from a victory, too.

Also, if you haven't already, (SPOILER)be sure to hit up the Imperial Base at the edge of the former Esper World if you earned that right from the banquet with Gestahl. And remember to check the fireplace for a Flame Sabre.

Thirdly, (SPOILER)there's a lone house to the north of Kohlingen. Go there and check one of the pots for a Hero Ring. I just like 'em myself.

Fourthly, (SPOILER)go to Tzen and find the guy among the trees selling the Sraphim Esper for 3000 GP. If you're heading to the Floating Continent, it's well worth the money spent. You can also get it later for 10 GP in the WOR.

Fifthly, (SPOILER)get all of Mog's Dances, if you haven't already. You won't be able to get Water Rondo in the WOR, and it's simple to get around to the other areas to get the other dances. To get the Water Rondo, land the airship in the Veldt and take the Serpent Trench back to Nikeah. From there, head north and then east across the continent. After a little while, you should recognize the isolated house from Sabin's scenario, so just follow the same path through the Phantom Forest that you did before and make your way back to the Veldt and your airship.

That's all I can think of for now.