My understanding of adult beverages at DL....only at Club 33. And can't help as to where with DCA...but I think you can get some yummy adult stuff there.
You can buy beer and wine at DCA, but not at Disneyland. Flo's has beer/wine as does Ariel's. Not sure where else, as those were the only 2 places we had any.
In DCA, they have The Mad T Party that like an outdoor dance club. They is a drink booth called "drink me" that serves yummy frozen adult beverages. You can find it on the left of the backlot by Monsters Inc..
There is no alcohol available to the general public in Disneyland (so if you heard that rumor, it is not true). Club 33 members and their guests can purchase it inside the club, but that's the only exception.
DCA has many options. There is beer and wine available in many restaurants, margaritas are available at the wharf, Carthay Circle has liquor as does the Cove Bar, and as previously mentioned, the Mad T Party has drinks as well.
There's a great frozen drink at Cozy Cone Motel in Cars Land in DCA that I LOVE! It's called a Pomegranate Limeade and it is YUM-MY! You can get it with or without alcohol (vodka). I wasn't sure if I was going to like it, but tried it once and I am addicted! LOVE it!
There's also the Karl Strauss beer truck.
OP, there is new restaurant opening in the Magic Kingdom at WDW that will be the first to serve alcohol inside Disney's Magic Kingdom. Perhaps that is what you read about as alcohol is indeed not served to the general public anywhere inside Disneyland.
In DCA at the Cove Bar they have 2 drinks, that I know of, that are not listed on the menu. The first, I've never personally had, is called a "Zombie" I believe it is quite possibly the strongest drink you can get, heavy on the rum (light, dark, and 151) along with tropical juices that make it bright green.
The other is, my absolute FAVE, the "Black Pearl". It is basically a long island iced tea, but with sprite instead of cola and the addition of Chambord (black raspberry liqueur). It's know as "Purple Haze" at the Hard Rock restaurants. They usually run around the same price $8 or $9 and are worth it. DBF and I make it a tradition to have them on our first day at the parks...after lunch (or while having "second lunch") of course!
You might be confusing this with the Magic Kingdom in Florida, where the Be Our Guest restaurant became the first location to serve wine/beer in that park.
The rumor OP is hearing is somewhat true. If the OP ever gets to attend a private party at Disneyland they are allowed to serve then. Also my favorite place to have a adult beverage or two is Trader Sam's.
Yes, at private parties, they can serve (example, the Orange Grove party for the 50th anniversary in the Festival Arena served drinks, as did this years Oktoberfest in Fantasyland.) But for someone just looking for an adult beverage during the day, other than Club 33, Disneyland is dry.
I do agree Carthay is at least equal to Napa Rose, if not slightly better.