"Smaller" and thinner cases will read more as a dress watch. Around 38 mm in my opinion is the best "dress" size case; I have ~7" wrist. Wrist size and case shape will matter though so let that be secondary. Dials can be colorful just not busy. If you stay with a neutral dial you'll have more room to play with different strap colors.
In addition to other suggestions:
There is a lot of variety in the Seiko 5 SNK/SNX watches for not a lot of money. I have a SNXF05 on a black ostrich strap and it looks very nice for ~$200 watch + strap.
Ill second the Citizen Tsuyosa also. Its a nice looking watch.
Didn't see automatic as a requirement so Quartz Tissot PRX is also a classic around the $300-400 range if you look around.
"Smaller" and thinner cases will read more as a dress watch. Around 38 mm in my opinion is the best "dress" size case; I have ~7" wrist. Wrist size and case shape will matter though so let that be secondary. Dials can be colorful just not busy. If you stay with a neutral dial you'll have more room to play with different strap colors.
In addition to other suggestions:
There is a lot of variety in the Seiko 5 SNK/SNX watches for not a lot of money. I have a SNXF05 on a black ostrich strap and it looks very nice for ~$200 watch + strap.
Ill second the Citizen Tsuyosa also. Its a nice looking watch.
Didn't see automatic as a requirement so Quartz Tissot PRX is also a classic around the $300-400 range if you look around.