Two completely contrary opinions:
- Don't ever let them watch "Idol" again.
- Spend 3 days at DLR (& dump the Hollywood day trip).
Seriously if i had a choice of driving to Hollywood for the day or spending the morning in Anaheim getting a root canal.....I'd go for the root canal (as long as i could spend the evening in DL).
I have to agree with Hound haha!!!
What type of food are you looking for? You will not find a lot of chains in the area but there are some things that are good. The food at Hollywood and Highland is mall type stuff and only ok. Though there is one sit down place.
There is an great Japanese place by Hollywood Blvd, that has the most amazing view of the whole valley and beautiful gardens to walk. There is a great Thai place near Griffith park, that is very themed and has great food (though you would never guess it from the strip mall look outside). I know a great Thai place with a Hollywood Rock feel on Sunset near the Whiskey and the Guitar Center (famous for musicans!). And a great Morrocan place in the same area. We have done lunch twice at London (Gordan Ramsey's restaurant in Hollywood), the lunch meal is reasonably priced and so good!!!
Ok since some of those options might be too odd for your kid's Johnny Rockets is also a great burger joint with .05 juke boxes on all the tables and occassional singing servers. There is an Italian place right near Universal Studios that has Singing servers the place is famous and amazing though I would make sure to get reservations for this place!!!
Ok if you really want to do Hollywood I have some suggestions for you as a local. Personally if you still want to do Hollywood I might skip Griffith, though personally I would rather do Griffith over Hollywood.
I would suggest either taking the bus tour or driving to Universal Studios, spend the afternoon there, it has rides its fun and the best part totally unique to this park is the backstage tour! This tour takes you through real sets that have been used on so many famous movies and TV and they still film there today. You can occassionally come up on then filming while you are on the tour. I always loved this tour as a kid. It might also be interesting as they have been rebuilding a large section of the backlot after a fire destroyed some famous sets including the one used for Back to the Future
Then you can walk around Citywalk, this was where Disney got the idea for DTD. The interesting thing about Citywalk (besides some fun shops) is they do a lot of filming up in this location as well. Many reality shows with competitions have filmed here, and concerts and signings. There are also some good restaurants like Buca de Beppo (Italian), a Mexican place, and Hard Rock. I would possibly have dinner here, then head over to Hollywood and Highland.
If you are driving Hollywood and Highland is like one exit up the freeway from Universal so easy to find! Go to the Hollywood and Highland complex, look at the shops, walk to the balcony where you can see the sign. Then go to the street see the stars, walk up the street a bit and there is Mann's. If you still have room cross the street and get some ice cream at the Disney Malt Shop, or just look around the world's smallest
Disney Store as I call it

I would not leave Hollywood till 8pm as I think that is the best marker for lessing traffic.
Again this is a plan I have done similarly with tourists before, I just don't want you to fight a lot of traffic to be disappointed by the offerings. Also I would hate to see you waste all of your day in traffic.