1. Honestly: a good musical experience
2. I'm usually tired after a day of work, so my general attitude is "let's get this over with". Once inside the hall, however, I usually wake up and I'm all excited. Also, I am worried about who is going to sit next to me and if I will have enough leg room (can't enjoy a concert if I have to contort myself).
3. I do study the material to find out when I am supposed to applaud

Seriously, I found I enjoy the concert more if I don't study too much, otherwise I go into the concert with pre-conceived notions.
4. If I can make it, I attend the pre-concert lectures. They are usually very good and definitely enhance the experience. It's a bit nerdy, though. Other than that, I am looking forward to learn about music from unknown composers.
5. I am generally looking for positives, but I am definitely noticing negatives, and they do have a great impact on how I enjoy the concert overall. For example, I hate it when soloists play cadenzas that are clearly not in the style of the piece. I don't like show-offs, and I don't particularly like it when it is clear that the musicians are not putting in their best efforts.
6. Only occasionally.
7. I have season tickets to the Symphony. For recitals and other concerts, time and price affect my decisions. Sometimes, I go to see a "legend" (you never know how long they are going to stick around).
8. I am terribly distracted by inconsiderate people, i.e. those who come too late, constantly drop their playbills, talk during the music, cough without making any effort to dampen the noise, people with breathing apparatuses. This can ruin whole pieces for me. For these reasons, I often enjoy a good recording more than a live experience. However, then there are those performances where I don't register any of that, and then I know that I had a really good time.