In Nov'03, we did the Fantasmic Dinner Package and ate at Hollywood and Vine. We ate about 1 and a half hours before and had no problem getting to the meeting area.
Bring your walking shoes as its a long walk sometimes uphill to the arena area. Pretty hard on a full stomach.
Anyway, the arena was not so full and we could've just gone w/o the dinner package and gotten a great seat. May have been the time of year or week.
I'm not doing the dining package this time as we are on the dining plan and the Fantasmic package is not covered. I would rather use my dining credits on other non-MGM Studios restaurants anyway. Not too impressed with them.
The show itself is great! The kids really loved it! Beware of the vendors selling popcorn and glowy sparkling lights and ice cube drinks. You may want to warn your kids about what they can have before you arrive as many of the kids pestered their parents for that stuff. I was lucky and brought lighty up things for my kids and was glad I did as that long uphill walk was partially in the dark!