For those unfamiliar with the original Golden Saucer, it was introduced way back in Final Fantasy 7 (and to my knowledge was never re-introduced in any other Final Fantasy game). It was a giant amusement park and acted like one in the game with all manner of mini-games. It also had some interesting rewards like Cloud's final limit break, Omnislash, in the Battle Square mini-game (fun fact, my brother managed to obtain Omnislash on the first disc of the game by grinding out 50+ levels in random encounters and then taking his super powered Cloud to the Battle Square to win the Omnislash manual).
Many of the mini-games recreated some of the sequences in the game like the bike battle (my favourite) or the submarine battle (also a favourite of mine) while others were more traditional carnival/amusement park games like basketball toss or strong man games. And don't get me started on Chocobo Racing and breeding.
In FF14 the Saucer pretty much does the same thing. It has lots of mini-games, a bunch of random events, chocobo racing and Triple Triad! I never played Final Fantasy 8 so I had no idea what Triple Triad was other than it was a game within FF8, It's fun and you get to collect cards and use your cards to win more Golden Saucer points (the currency within the Golden Saucer).
At the moment the rewards at the Golden Saucer are cosmetic items, chocobo racing items or Triple Triad cards. I got lucky and managed to win 10,000 golden saucer points from a mini-lottery and bought a new hair style (only available at the golden saucer).
Then I spent the leftover points on racing feed (though I still have to actually race my chocobo). I won another mini-lottery and will probably save the points for some of the cosmetic weapons for my other classes when/if I get them to 50.
Little things like this definitely make this game nicer than other MMOs I've played.