SE Hawthorne Blvd is fun from about 10th to 50th, with the highest concentration of stuff from 30th-40th. SE Belmont is parallel and the fun stuff is most concentrated maybe around 35th.
SE Division is the other high street parallel to those, it's fine and has some good places to eat but is a little more ritzy.
NE Alberta, N Mississippi, N Williams are also fun areas - just look on a map for the area that looks built up and full of restaurants and bars and go there.