Encontrarse a / con

[fglorca]

Siempre me encuentro a los vecinos por las mañanas:

I think this one means that you see them from a distance, but you don't say hello. A translation might be:
- I always 'spot' my neighbours in the mornings.


Siempre me encuentro con los vecinos por las mañanas:

I think this one means that you see them, and that you also say hello to them i.e., you greet them. A possible translation:
- I always 'bump into' my neighbours in the mornings.

Clarification on this would be hugely appreciated.
Thanks in advance.

[Rusty]

The explanations for the examples you gave are correct.
The 'encontrarse a' structure means seeing someone, maybe from a distance, but not stopping to talk with them. You spotted someone.
The intransitive construction, with 'con', means that you said something to someone that you saw. You're face-to-face.

[AngelicaDeAlquezar]

I agree with Rusty, but I'll add a note:

In Mexican colloquial speech, "siempre me encuentro a mis vecinos" may include interaction between you and your neighbors (you may or not greet or talk to them), but you didn't plan that meeting; in this case, it simply means that you all leave your homes at the same time, and the coincidence makes you see one another. => I always see my neighbours / I always bump into them.

"Siempre me encuentro con los vecinos" may be a synonymous sentence, but depending on the context, you may have planned those meetings. => I always meet my neighbours (with a purpose) / I always bump into them.

[fglorca]

Many thanks!