Hi there, I lived in Denver as a single young woman a couple years ago. If possible, I would stay in Denver just to be close to where everyone is. I lived in three locations - Cherry Creek (south of Speer), Golden Triangle and Cherry Creek North. To be honest, I didn't feel 100% safe in Golden Triangle. I felt totally safe in Cherry Creek and loved the neighborhood, but that's not near Light Rail. A few of my friends lived in Lodo and the Ballpark area in Denver, both of which are very close to light rail. Some of the apartments have set-asides for medium-income people called affordable housing (it's not section 8). A few of my friends who were just starting out were able to get pretty great lofts under the affordable housing set-aside.
You may think twice before moving near Colfax or in the Capitol Hill or Uptown neighborhoods - although, the areas are more affordable. The best way, in my opinion, is to take a drive in the area you are considering at about 10 p.m. to see if you feel comfortable. Although, not so easy if you are in Baltimore. :) Denver has a large homeless population, most of which are fairly harmless, but sometimes individuals made me uneasy.
If you don't care about living in Denver, you may also check out the Denver Tech Center, which is at the South end of the Light Rail system. There seems to be something of a nightlife there. Plus, there are some terrific restaurants.
You may want to check out this map - www.spotcrime.com. It will show you where the crime is in Denver, or surrounding towns.
That said, Denver is a great place to live. Compared to Baltimore the crime is minimal, there's a lot to do outdoors and the population is generally young. Plus, it's sunny about 350 days a year, or something ridiculous like that. Good luck! Let me know if you have any questions - I'm happy to help!