I shop at a lot of places, and have a variety of tastes. However, I think my most 'fashionable' clothes, the ones I put on when dressing up or going out, come from Express Men. Yeah, they have a lot of
'metro' things, but if you look past the pink and the paisleys, they have a lot of nice clothes. You can't go wrong with a nice button down shirt and dress slacks.
As an alternative, and a more urban look,
dickies pants rule. You put a crease in them, and they still look nice, they are pretty rugged, and they go well with most things.
I try to stay away from current fashions. You'll see a lot of metrosexual things, i.e. mens shirts with lots of pink, floral patterns, french cut sleeves, etc, a more feminine look. The other trend is the beach bum look, threadbare $80 jeans with the premade holes and fades, $40 t-shirts with some silly slogan, made to look like a vintage ad and usually suggest something sexual.
When in doubt, I'd say go for a clean cut look. Casual, not to square, but not so relaxed your wardrobe makes you look like you are on spring break 300 days a year.
Then again, what do I know? I am 27 and married, and current fashions and trends I don't keep up with.