For more or less tailored apparel I would suggest these:
-Stockmann, a large department store
-Solo For Men, a large, specialized selection
-Fere, a small high-end store with the finest makers
-Vaatturiliike Sauma, a tailoring store with an interesting selection of Italian makers
-E.R. Wahlman, a specialized hat store
All of these have websites with more or less info in english.
For additional info:
Do let me know if I can...