A good 2nd lens for 2-lens outfit?

I currently shoot with a Canon T2i.  I have a Canon 70-200 f4 IS USM lens, and would like suggestions for a second lens.  I have other cameras.  So a 2 lens DSLR outfit is really all I require.

Here's what I expect to use it for: scenics (SW territory), landscapes, family events, parades, cityscapes, general walkaround.  That's a lot of subjects for just one lens, I know.  I can't afford the 24-105 "L" lens.  I've considered the 15-85mm lens, but wondered if I could get anything for a little less.  Yet I still want something with better IQ than than a 18-55 kit lens, and need it to be a bit longer as well.  Doesn't have to be Canon brand.

Any suggestions will be seriously considered.  Thanks.