Office fashion for young men.

Dear All,

I have got an important question for you, I though many other people would also be interested to know so I am here with my question.
I'm a young consultant (23 years), and in my organization there's the culture of 4 days business casual with 5th being the casual dress day.
Mostly the people just dress what they want, mostly with a trouser and shirt (I add a tie to look more professional, but no blazer) and others with jeans and shirt (no funny ones).
In my wardrobe I have plenty of shirts, trousers and ties (and tie pins of course ;) ), but this is okay when I am in the office. When I have to be on client sides (and have to travel back and forth from office every week), it is preferred to be in informal clothing (blazer n tie) which some people refer to as formal clothing (which the really formal includes bow tie and probably a tux).
I have a thing for travelling smart, and I can't carry 2-3 pieces of suit with me to the hotel every week. I was wondering if anyone could suggest, what kind of blazers should I buy, which (one per week) i can wear with different trousers and shirts combination ? What's the kind and colors that I should look for? What textures? Colors? Cloth type? I need some help here.

Another question revolves around neck ties, I would like to ask, if anyone know about the different types of neck ties, some are broad some are narrower and some are made of thinner cloth than the other. Is there a purpose, e.g. one has to be wore with blazer the other one not etc ?
I personally like the ones, which are a little narrower, coz they are realtively easy to handle.

I would definitely appreciate your kind responses, looking forward to it!