The relationship between the jack-in-the-box father and son in "Out of the Box" and "Chip Off the Ol' Box," especially in the latter when the father gets injured. The son is very worried about him, but the father assures him that it'll be alright and tells him that he knows he can be brave.
The "Hey, What's Going On?" song can be very touching, especially in those cases where Doc sings it really softly to comfort.
Donnie never seems to mind if Doc plays with his toys, or even in his room. Of course, Doc likely fixes his toys whenever he needs it, but it's still pretty nice how laid-back he is about letting her play with his stuff.
Doc singing "I'll Never Stop Loving A Toy" in "Welcome to McStuffinsville."
Doc apologizing to Lambie for neglecting her for Val and telling her she'll always love her in "My Huggy Valentine".
Peter Cullen getting to reprise his role as Eeyore for the first time in six years for the Pooh crossover.
The Winnie-the-Pooh crossover episode Hundred Acre Wood is filled with touching and charming interactions between Doc (along with her stuffed animal friends) and Pooh and his friends. One example is Doc first noticing Winnie The Pooh flying and actually getting excited to see him before she and her stuffed animals prepare to rescue him. In the episode, Pooh is spotted flying in his balloon outside of Doc's Toy Hospital to get some honey for the Honey Festival. But it's so windy that it reroutes Pooh and Doc has to rescue him. Eventually, Pooh gets rescued in the Hundred Acre Wood but injures his stomach as a result. After Doc takes care of his injury, Pooh is disappointed that he missed the Honey Festival until Doc and friends bring the Honey Festival to him outside of her hospital.
One of the sweetest and cutest character interactions would have to be Lambie and Piglet. Piglet is very worried about his best friend Pooh, and first meets Lambie by searching inside a tree stump. Eventually they bump into each other and get along so well that Lambie says "Pink pals stick together" while giving him a hug. Later, when Pooh is taken to the hospital, he is seen anxiously running behind Pooh, but Lambie quickly grabs him to let Doc handle the situation. She then tells Piglet to not be scared and lets him know that even she is worried and hopes he gets better, followed by her giving him a hug with Piglet responding by saying "Me to, Me to.". During Pooh's operation, Lambie and Piglet have a conversation about what to do until they think of a plan.
One episode from Toy Hospital called Lambie Stuffy Switcheroo shows Lambie taking care of babies in a nursery and singing them a lullaby as they go to sleep.