You can also try to walk up. We were able to at a few spots, and I saw others doing it. This was even when the reservations had told us the restaurant (Kona for us) was full.
Anyway, we were there in early August. We had very nice dinners at Tusker House and Brown Derby.
We had nice lunches at 50s Prime Time and Studio Catering Company in DHS.
Last year, we liked our dinner at Mama Melrose too.