You can read a bit about the Fantasmic Dining Package
HERE. The restaurants are at three different prices points. The least expensive option would be Hollywood and Vine. Mama Melrose is a bit more and Brown Derby is the most expensive. (Exact pricing can be found by calling Disney Dining at 407-WDW-DINE.)
The Brown Derby is a wonderful signature dining restaurant with spectacular service, gourmet food, and an outstanding wine list. If you're looking for a superior meal, this is a great choice. But it sounds like you're more interested in something simpler. Hollywood and Vine is a standard WDW buffet. When I dined there earlier this year, there were plenty of choices on the line, but overall I found the food to be only fair. You'll have some decent options, but you won't be "wowed." The food quality at Mama Melrose is somewhere in the middle. There are some basic choices here like those you might find at an Italian restaurant at home, as well as some special Disney dishes.
You can take a look at the menus for all these restaurants by going to the website allearsnet.com and searching on the name of each restaurant and the word "menu."