The near west side is the hottest area in the city, it used to be blue collar warehouse and club districts, but now it's completely taken over by 20-30 somethings moving into the city from the burbs, and transplants working at tech and media companies and hospitals and finance. They even added and rehabbed train stations on the green line to make it even easier to get to the loop downtown. New bars and restaurants opening ever other week, companies moving their chicago offices there (Mcdonalds, Google, etc). There is still a very small pocket of hood on the direct outskirts that hasn't been condo'd out yet, but in a year or two it will be.
at about ashland it terns back into regular neighborhood where it's more mixed now, but not hyper gentrified so far. You can get a house townhome or apartment close to the hip area but still have the perils/benefits of living in the city outside of a bubble like the west loop i just described above.
Going directly west from downtown, anything past Western ave ALL the way til you hit Oak park would get a No from me dog. That's generally what people mean when they talk about the "West Side". I'm a southsider, and biased, but in general once my grandmother passed I had no reason to ever be anywhere in that part of the west side again. Westside niccas are just different man, lol.
North west and South west side neighborhoods are generally referred to by their specific neighborhood names and and run the gamut racially and income wise.