Whether you are a fan of free dining or not, Disney has extended the free dining plan promotion through the rest of the year (with notable gaps for any time of the year that is remotely busy). If you have any trip planned between now and the end of 2010, regardless of if you have the free dining plan or not, you're going to want to book your restaurant reservations (ADRs) as soon as possible.
The reason why you want to book reservations immediately, even if you aren't buying the free dining plan is because free dining promotions cause many more people to make restaurant reservations than normally do. Think about it, if you go on your own and pay cash, you may only book a sit down restaurant a few nights of your stay but if you have sit down meal credits for each day of your trip, then you're going to make reservations to use up those credits. So be sure to book ahead while there's still decent availability.
Ideally, we all make reservations 180 days in advance for any restaurant but even if you only manage to make an ADR 60 days or so ahead of time, you're still going to be okay. The restaurants at Hollywood Studios have great options for making reservations ahead of time and of course, you're going to want to maximize the value of your free dining credits. While you are getting the dining plan (at moderate and deluxe resorts) for "free", it behooves you to get as much value out of the dining plan as possible given you had to shell out more money for the hotel room (and of course for that gratifying feeling of having succeeded).
The only restaurant that you should avoid on the regular dining plan is the Hollywood Brown Derby, simply because it's two dining credits and any restaurant for two dining credits never makes financial sense if you do the math of what the credits are worth and what you are getting. Aside from the Brown Derby, the rest of the restaurants should be considered in play for you.
The 50's Prime Time Cafe and Mama Melrose's Ristorante Italiano stick out as good options for the dining plan given the price of entrees and the great food there. In addition, I'll also recommend Hollywood & Vine for dinner even though it isn't the best value on the dining plan. The reason I will recommend Hollywood & Vine is because the wide selection of food and good options make up for the lack in value in this case.
When trying to make ADRs, there are some good tricks to use in case you aren't getting results for the time you want...
If you can't find something you're happy with at Hollywood Studios for a sit down meal, don't give up. Remember, there's lots of restaurants a quick boat ride or walk away in the Boardwalk area. From the Yacht and Beach Club to Swan and Dolphin, there are lots of restaurants available and the commuting distance to them is very manageable to be able to still swing back to the Studios after.
Whether you're on the counter service dining plan or the regular dining plan, you'll have lots of snack credits to use at Hollywood Studios and if you're looking to maximize the value of your snack credit, it's hard to go wrong with a tasty treat at the newly refurbed Oasis Canteen. There, you can get a funnel cake with sugar for a dining credit. Considering it costs $4.29, it's a great option and will get you some of the best bang for your snack-credit on Disney World property.