After Many Days - this is one of the first short story collections from Montgomery that I ever read. All the stories revolve around time passing. Sometimes they're children adopted or otherwise or siblings coming back after making good. Sometimes they're couples being reunited after a long period of time.
Across the Miles - these stories all involve letters. There are several involving pen pal type relationships, one or two that involve letters from the past and at least one that has someone switching letters so that people don't necessarily get letters they're supposed to get but do get the one that they need to get.
Both of these collections were sweet and old fashioned. While they're not necessarily fine literature they are a fun break and I thoroughly enjoyed both books. I gave each of them 5 star ratings.
The Doctor's Sweetheart is a little different. There is no theme to the stories and the title comes from one of the longer stories in the collection. This feels like where the editor decided to put all the stories that didn't fit into the other books. Unfortunately, many of these were stories written very early in her career and they were a bit slow going. While I didn't dislike the stories I definitely didn't get the same level of enjoyment out of this one. I ended up rating it 3 stars.