I-94 from the Lowry Tunnel to Riverside Park, and I-35 from 22nd St to the Mississippi. That's a fantasy and a goal.

I think if this was to occur it would obviously come in stages, and have to leverage private investment, or be supported by it. As a first stage I think anything over I-35 between 6th St to 1st St would be a good place to start. Why? It's an area where there's a lot of private development already occurring as it's close to 2 current and 1 future light rail stops. A land bridge would re-connect two growing areas.

The area is already mixed-use, so it would be likely to generate a lot of pedestrian traffic.

I think they key to making these things work is to envision buildings as a central part of the design, rather than parks. Yes, include reasonable green space on the land bridge, but the idea that people will use a park on top of a freeway (in a city with lots of much better parks) is a waste of a good idea.