Yup, rezoning is key....at least in my semi expert opinion. Developers would build on the north side of 1st ave if they could build something more significant. It doesn't have to be anything major 4-6 storey mixed use would do the trick.
I'm inclined to agree with disco Stu, leave the taller buildings to the south side, and closer to Memorial. the north side of 1st should be 2-3 floor buildings. A building similar to Trolley on 17th ave would be perfect where LeBrezza is.
Oh and yes please to a bike lane.
In general, the north side of 1st really lets the entire street down. Apart from the LDV block, and Bridgeland Market being nice...it's a huge mish-mash of parking lots, residential, schools, etc. Hopefully the new rezoning proposals will help to kickstart some changes on that side to bring it all together.