I bike Grand Rapids nearly everyday, and oftentimes with my kids. This city has great potential to maximize efficiency with cars, buses, bikes and pedestrians. The approach I would take would be to make Grand Rapids a more bike friendly city.
The first change I would implement would be to eliminate the curb bumps out that proliferate the east side of the city. The bump outs force bikers to ride into the driving lane in order to cross through intersections. (Fuller Ave. is the most well known for this) The bump outs bring the sidewalk into the street and create a pinch point where there is only enough room for a car to pass through the intersection. This is not only dangerous, but inefficient because it does not allow bikes and cars to share the road at the same time.
My second proposition is to give Fulton a dedicated bike lane. Fulton is one of the main roads connecting the city east and west. Much of Fulton already has a bike lane and it would be ideal if the bike lane could continue through downtown. Bikers are willing to go out of their way in order to find a road that is bike friendly.
My third proposition is to make more roads downtown one way. One way streets are ideal for bike lanes and can make the city more efficient at the same time. Biking through downtown could improve greatly with actual bike lanes.
The last two changes would include bike sharing and continuing the path along the Grand River. I wouldn't advise implementing a bike sharing program until some more dedicated bike lanes have been carved out in the city.