What is the normal attire for eating out in Buenos Aires, and attire in general? I leave next week for an 8 day stay and am ready to start packing!

You don't say whether you are a guy or a gal. There is a recent thread on the subject on trip advisor.com

I would not mind info on both, since my wife will also be with me....From what I have read, it seems like casual days and semi dressy nights is appropriate...What about tango shows and teatro colon performances? We will be attending both while in BA....

See "weather in November" thread on tripadvisor.com

In October it should be only a little cooler than in November.

i was going to ask the same question. jeans or something nicer (like dockers)during the day? casual restaurant at night, i assume dockers and nice shirt (no jacket)? same for shows?

In Buenos Aires either dressy and sport-dressy are OK during the day and at night.

You'll see much people with jeans and jacket, or suit with t-shirt. Colon theatre attire is just as fancy restaurant. Most people atend colon performances in dressy clothes and you'll see some people in jeans and t-shirt (very few bohemians). To be safe semy dressy is always a good choice.