Welcome to planDisney, Jillian!
California Grill is my favorite restaurant at the Walt Disney World Resort. I remember the first time my wife and I visited this restaurant. We couldn't get dining reservations, yet, we managed to get a seat at the bar. We ordered some very tasty beers and watched the fireworks from the outside deck. It's one of our most magical memories.
You'll be glad to know that the lounge at California Grill is first come, first served. In fact, if you don't have a dining reservation, they only allow you to take the elevator up to the restaurant if there is space in the lounge. At the moment, the bar mainly serves drinks. However, you're able to order a cheese board to go with your beverages. I had a Cast Member confirm that for me.
Finally, when it comes to returning to the restaurant for the fireworks, there doesn't seem to be a policy regarding the lounge specifically. However, Guests who have dined at California Grill earlier in the evening may return with their receipt. If I were you, I'd check with a Cast Member when you arrive at
Disney's Contemporary Resort. I do know that, for safety reasons, the restaurant can only fit a certain number of Guests. Once they reach their maximum, they no longer let people up. Therefore, if you'd like to watch the show, your best bet might be to maybe let some of that cheese age for a few more minutes and order another drink. Having watched the nighttime spectacular a few times from California Grill, I can testify that it'll be worth the wait!
One more piece of advice: Guests at or visiting Disney's Contemporary Resort can also view fireworks from the north end of the 4th floor. You'll still get views of
Cinderella Castle and
Magic Kingdom Park, as well as be able to hear the background music.
I hope that's helpful, Jillian. Thanks so much for stopping by planDisney!
Mike