If you called the number and they are all booked then there will be no walk up reservations taken that day. They stopped that when Priority Seating Reservations were set up; well let me rephrase that, you can make same day reservations, but Blue Bayou books so fast there is a slim chance of getting one. You can go and wait at the restaurant for a table without a reservation, that still is an option. But you could stand to wait up to an hour at the most. There are a few other nice restaurants you could go to, but they won't have the ambiance that Blue Bayou has.
California Adventure has a nice restaurant if you are looking for upscale, romantic. It is called The Vineyard Room. I have not eaten there personally, but I have heard from a lot of regular park goers that it has good American style food and the prices are moderate.
For a more casual, but still really nice restaurant, Ariel's Grotto in DCA is a possibility. You can request to sit out by the water and watch the water, people, and/or roller coaster. They have a set price for all the food, like $23. That includes appetizer, entree, dessert and drink. They have an awesome Churro dessert with ice cream and chocolate and caramel syrup, yum!
If price is not too much of an issue, Hook's Pointe at the Disneyland Hotel is good. It serves seafood and steak mostly. It also has a romantic feel and if you have never been over to the Disneyland Hotel, it is beautiful.
Another steakhouse at the Disneyland Hotel is Steakhouse 55. Good food, but is on the high side cost wise as well. Not as romantic, but a nice contemporary restaurant.
(714)781-DINE ... if you want to eat at a specific place always call at least 2-3 weeks before your trip. Then you can guarentee you can eat at the restaurant at the time you want. Have fun!