Solo Trip to Iberia in November - Lisbon, Madrid, Barcelona, or All Three?

I'm currently heavily considering going to Iberia in November from NYC. My thought is that flights are way less expensive, and the temperature is still going to be quite mild and comfortable (I grew up in the Northern Midwest, so cold doesn't start until like 20 degrees), so I'll still enjoy it, and my wallet will thank me.

I'll be 24 by the time I fly out, and it'll be my first solo trip. I'm thinking of going to Lisbon, Madrid, and Barcelona, OR Lisbon and leaving one of the Spanish cities out. I plan to stay in hostels; it doesn't have to be super party-oriented, but at least very social. I also don't plan on planning things out too much. I'm really just the type that wants to roam, engage in the street life, and have some fun nightlife. I did a road trip into Canada like that and made my way to Toronto and really enjoyed it, a lot more than if I did the things I was "supposed to do."

My thought is this: I'll probably have like 9 days, so three cities is a decent bit, but I also don't think I'm the type that needs to see every last thing in the city, so maybe a few days of roaming and going out to raves and whatever else will be enough to scratch my itch for each city. Do you think it'd be best to stay an extra day or two and keep it to only two cities, or will I probably be happier if I get around to all three? Feeling really 50:50 even after consideration and some research.