OK, some of you will think me TOTALLY strange for saying this but seriously, if you are thinking of breeding a mare in the spring/summer of 2008 then this is the right time of year to be looking at stallions.
He will be in his winter coat, most likely a bit rough, this will mean you see the stallion at his worst in terms of body condition. You will be seeing the true horse not some show-shine-covered sparkly thing. If he is a hard keeper you will be able to tell this in the winter as that is something very often passed on to foals so you will want to know this before you confirm you want to use him for breeding.
You will see him out of working season which will mean you will be more likely to see his true character rather than the hormone-adjusted hyped-up twinkle toes of a stallion who is snorting his way down the yard trying to get the attention of all the girls, in short his head will be on the job of ridden work in the winter so you can see his "normal" movement and not what hes like when his head is only on where his next mare is coming from. This will mean you will see his true temperament for work rather than his hormonal issues. Afterall, how many colts born from him will be kept as stallions? Very few I'd guess, so don't you want to know what the temperament is like when hormones are not running away with his one remaining braincell?
You can have a look at his weanlings and older offspring. You will be able to see how his older offspring hold their weight and how they move when they too are not charged up with hormones.
Whilst I do think that seeing his temperament is important during normal stud season, hormone levels can change from day to day, horse to horse etc and you can get things to help with hormonal issues. However, seeing a stallion when he's all up on his toes after the mares... he will always impress someone with his movement, but how about in the winter when there are no hormonal mares egging him on?