The Ariel Meet N Greet is no more, whether it's an idea that is gone permanently, or one that they have just giving up on for now, is a question that only time will tell. Ariel is almost always at the princess area to greet, so I really think she doesn't need a separate meet n greet area like she had at Disneyland once upon a time. I remember a time when Disneyland was so congested with characters that you couldn't get down Main Street if you wanted to see them all. My highest total for a single day of characters was 18, and that was long before official princess meet n greets and the Winnie The Pooh section.
That all being said, you can always count on Winnie The Pooh and friends in Critter Country, the princesses in Fantasyland, usually the Fairy Godmother and Snow White near the wishing well, Rapunzel in the afternoon, Merida from Brave in her area, Cruella near the fire house, and Alice and the gang at musical chairs. Beyond that there is always Duffy over at DCA.
For the most characters, definitely a character meal is your best bet.
That's a good collection of some of the hot spots. I was in DL at the end of July and was on a character hunt, also. Here are a few other characters to be on the lookout for at the DLR.
Snow White wishing well: in addition to Snow White and Cinderella's Fairy Godmother, you may also see the Evil Queen from Snow White.
At Princess Fantasy Fair, if you go to the Tangled show, Rapunzel and Flynn (aka Eugene Fitzherbert) have a meet and greet, as does Belle after the Beauty and the Beast show.
Toontown: Mickey's House for Mickey (in different outfits, depending upon what stage you go to), Minnie's house - Minnie, Goofy at the front of Goofy's House. Pluto is sometimes seen near the fire house.
Tinkerbell's meet and greet area between the cast and Tomorrowland: Tink and her fairy friends
Tomorrowland Terrace: Darth Vader, Storm Troopers, etc.
One of the COOLEST character photos you can get is: if you can find a Photopass Photographer near the Haunted Mansion, you can get your photo taken with the Hitch-hiking Ghosts! Ask for the MAGIC PHOTO. Sure, it may not seem like you've had a meet and greet, but wait until you see the photo!!!!!
Alice and Crew are sometimes at Coke Corner doing musical chairs around noon or 1. I also saw Mary Poppins and Bert near the Poppins cafe by Coke Corner.
Aladdin and Jasmine can be found in Aladdin's Oasis in Adventureland.
Back in Big Thunder you can see Bulleye on stage. For meet and greets in Big Thunder Ranch you can find the following in their western wear: Jessie, Mickey, Miinnie, Goofy, Chip and Dale.
Ran into Pocahontas on Big Thunder Trail
When you enter the DL gates, be on the lookout for characters, as a variety can be found their. Of course Pluto, Mickey, Minnie, Cruella, and others can be found in Town Square.
Over in DCA, on Buena Vista Street, many of the same characters, but in their 1920's finest wear, Goofy, Mickey, Chip and Dale, Pluto. In Condor Flats,
Minnie in her Aviator attire.
Redwood Creek Challenge Trail Dug and Russell.
Near Playhouse Disney, Sofia and Jake
Photo opp for Monsters U , Sulley and Mike with braces
In front of the Animation Building : Mr Incredible
Photo Opp for Chase Visa Cardholders: Minnie or Stitch
Radiator Springs : Lighting McQueen, Matar, Red (Firetruck), DJ,
Near Midway Mania: Woody, Buzz
Meet and Greet by Cove Bar: Donald Duck (also Duffy meet and greet is close by)
In addition, Disney Blog announced another chance to meet some more rare character later in August. They had quite a wonderful assortment, earlier this year for a similar weekend.
Oh, and if you make it to Dancing with Disney, you will get a chance to get up close with some characters for Dancing and a possible un-posed photo, BUT NO AUTOGRAPH characters range from : Cruella, Marie (Aristocats), Anastasia, Drucilla, Timon, Genie, Hook, Smee, Daisy, Clarabelle, and others.