I'm 31 and lived in the NW for the past 4 years. I have loved it and always felt safe. However, there are many neighborhoods on the east side that have great ambiance, walkable, trendy and great restaurants and neighborhood bars. A great place to get acquainted with different neighborhoods online is http://www.neighborhoodnotes.com.
Let me know if you have more questions and I'd be happy to point you in the right direction.
Call or write with any questions!
Janeese Jackson, Principal Broker
Real Estate Resource
Just below the Alphabet District is The Pearl. Pearl is made up of converted warehouses and newer hi rise buidlings. You can expect rents to be higher in the Pearl. Look at rentals from Couch to Overton and from Park Ave to 14th Ave. Avoid the condos on the river if you like to walk. While safe during the day it's a little removed from the Pearl and can feel desolate in the evening. Probably best to avoid Old Town, while there are a fewer newer buildings and the lower rent might seem appealing - I wouldn't recommend it.
There are some hi rise towers and smaller historic bldgs in the downtown area from SW 17th to Vista that might interest you. Not too far from 23rd Ave or the Pearl but also not outside your door.
The Eastside has some great areas as well. Consider Hawthorne, Belmont, Alberta and Division/Clinton neighborhoods. If you stay between 15th Ave and 39th Ave in SE and between 15th and 33rd Ave in NE you will stay in the hub of restaurants and bars.
If I can answer any other questions - give me a shout!