Good question, about which I too have wondered.
I imagine that the answer varies from country to country and from athlete to athlete, but a few anecdotal memories from Vancouver indicate that at least some do choose their own roommates:
- At the time of the Vancouver Games, Charlie White and Evan Bates were roommates at home in Michigan (along with Alex Shibutani and another skater).
White and Bates also were roommates in Vancouver. Doubt that was a coincidence of assignment by USFS ... assume that they chose each other.
[BTW, very cool that the three former roommates in Michigan -- White, Bates, Shib -- are the three male ice dancers for Team USA in Sochi.]
- Tanith Belbin and Johnny Weir were (platonic, presumably

) roommates in Vancouver. Based on comments that they made at the time, I'm sure that they chose each other.
- In Vancouver, Patrick Chan shared a bedroom with Bryce Davison, and a suite with Scott Moir and V. Chipeur (sp?).
In Patrick's YouTube video tour of their suite, he made an offhand remark to the effect that he always roomed with Bryce. Again, I assume that was no coincidence.