Lots of other CAD programs have the ability to directly create a line with a line at a given offset. For example, an inner and outer wall.
Furthermore, the ability to specify "inner", "outer" (or "left"/"right") and/or "both" (symetrical) offsets would be nice, too.
Another option to leave or remove the "base" line would be good to. (Maybe you wanted to keep ONLY the offset line, or the outer lines, but not the middle one).
On that note - inner/outer/symetrical options (particularly "symetrical") options would be nice options for the existing sketch "offset" feature.
Another good option would be to "automatically" create the "base" line as a construction line. This would mean I would (for example) create a "base" line as a midpoint (which would become only a construct line) - and left-and-right "symetrical" outer lines to create a "wall" with thickness. Afterwards, I could only change the (middle/base) "construction" line - and the outer lines would parametrically fix themsleves.
Right now - I often have to draw a line, make an offset to the line (on one side), then an offset to the other side, then delete the center line to create a "wall with thickness". I should be able to do this in a single operation.