You know you've been waiting for it: my season three predictions for Meredith. Well well well. Today is your lucky day.
Meredith doesn't choose either Vet-Guy nor McDreamy. That would be too easy. Meredith wants to really work to get someone because she thickheaded so will pass on these two stallions. In the beginning of Season 3 she will simply swear off men (again) but by midseason she'll have some new crush. This new crush will totally hate her at first and won't be a doctor. She'll probably even hate him since that's the way TV love works.
Her mom, sadly (arguably sadly), will die in Season 3 and it will happen right after Meredith gets with Mystery Guy for the first time putting him in a very awkward spot. Sure he wants to keep poking her but does he really want to be "the guy" for some girl he used to hate and that he just got with? Probably not so he'll have to leave. Now Meredith will be doubly devastated and get back with Derek because hey, that's what she does.