The key to the city
There is a way to get back into Midgar, without going through the assault. Instead of flying over Midgar, land and walk into it. Here you will see a man standing next to the Sector 7 Gate. If you talk to him, you will find that he thinks he lost his key "at that excavation site". Well, there is only one of those found in the world. Hop on the Highwind, and travel to Bone Village. Here, ask to look for "normal treasure", and place the men in the top area. With any luck, you will get the key. You can now return to Midgar, and head on in. This is the only way to get Tifa's Premium Heart, and the Sneak Glove Accessory.

Crashed Gelnika
The Gelnika plane crashed off the Costa Del Sol shore. It was en-route to deliver massive weapons to destroy Meteor. It is assumed that WEAPON sent it to the ocean floor.

*WARNING* Emerald WEAPON is roaming the ocean floor. He may be in front of the plane when you get there, or leave. To get him to move, simply surface and dive again. But above all, save before you dive, and when you leave the Gelnika. You really do not want to risk running into him!

The Gelnika is one of the more dangerous places in the game. It is in your best interest to save, even if you saved on shore. The entrance is monster free, and you are able to get your first item. It is Cloud's Heaven's Cloud Sword.

In the door to Clouds right, you will find the Generator Room. In here you will discover the Escort Guard, Double-Cut Materia, 2 Megalixirs, and Yuffie's ultimate weapon Conformer. (The Conformer, and Double-Cut Materia are well concealed. Just look in both top corners for them)
Return to the entrance, and head into the room to the left. Here you will fight Rude and Reno. (Only if you have not fought them in the Midgar assault yet)

Boss Firght: Reno & Rude

This is a pretty straight forward fight with the guys. Set up Big Guard and Regen right off the bat. Make sure someone ahs the ability to steal from both, as they are both carrying some great items. Rude has his usual punch attack that can do close to 1000 HP damage. He seemingly is more active than Reno. So you might want to go after him first. Reno uses his wand more than not, and can also confuse a character. If you do not have Ribbons, try to equip something to prevent confusion. Basically this fight will end pretty quickly. It is not near as tough as the fight coming in Midgar. It certainly is easier to survive than the fight with most the enemies on the plane.

After the battle, continue to the next room.

This is the Hangar, and where all the real goodies are. On the top tier, you will find 2 more Megalixirs, and Cid's Spirit Lance. On the bottom, you will find the Hades Materia, Vincent's Outsider, and Cid's Highwind Limit Break.
Be very careful roaming around in here. Shinra has some nasty abominations for you to fight. If you are strong enough, each Unknown morphs into a different source item. This is a great way to max some of your characters stats out. A fast way to beat them is have a Added Effect+Gravity on your weapon, and morph away!
When you are done and ready to leave, you need to SAVE! If you run into WEAPON outside, you will die. Do you really want to go through this again??

Vacation home for sale
In Costa Del Sol, there is a home for sale. When you first speak to the man on the bed, he will comment about no one ever having enough Gil to be serious about buying it. Well, he is right. On Disk one, unless you cheated, or spent an obscene amount of time leveling up, you do not have the Gil to buy the home. The home is going for the incredibly low price of 300,000 Gil!
However, after Disk 2/3, after you have amassed a small fortune, you will then be taken more seriously by the seller. He will hand over the keys, and be on his way. There is not much you can do here, accept for resting for free. But there are some nice prizes in the basement, (Motor Drive, Power source, and Fire Ring) that you can get at any time.

Turtle Paradise flyer give away
Wutai's Turtle Paradise is having a promotional give-away. If you can spot their six flyers scattered across the world, they will give you a pretty descent reward. Here is the locations of these elusive flyers.

FLYER #1	FLYER #2	FLYER #3
The first flyer is in the top floor of the eastern-most house of sector 5. This one needs to be obtained before the Pillar Assault Mission.	The second is inside Shinra HQ. it is in the lobby in the back area. If you do not get this one on one of your two visits here, you missed out!	Flyer #3 is located in the lobby of the Ghost Hotel, inside Gold Saucer.
FLYER #4	FLYER #5	FLYER #6
The fourth flyer is hanging on the eapon sellers stand, in Cosmo Canyon.	The fifth flyer is next door to the fourth, at the inn in Cosmo Canyon.	The final flier is in Wutai itself. It is on the wall in Yuffie's basement.

Ok, I bet you are wanting to know what the pay off is for getting all 6 fliers huh? Well if you return to Wutai, and talk to the bar keep, he will give you one of each source item, and a Megalixir. Not a bad prize at all, considering you really did nothing to get them.