This is also the chicken/egg situation. If we got rid of a lot of surface parking, a shuttle/circulator bus or trolley would be used. We can't get rid of the surface parking (as much as we should) until there is circulator transit to get around.
Thats where the idea of, instead of spending millions on new parking garages, we instead put the money towards a downtown circulator route. No the route won't be used all the time and there will be times when the bus is empty, but the same thing holds true with parking garages.
1. Determine a dedicated route and put it on maps around downtown.
2. Have unique looking bus shelters/stops on the route that also act as info centers for times of operation and amount of time before bus arrives.
3. Make the bus readily identifiable and distinct looking.
4. Promotional/awareness campaign on radio, tv and signage around town. (which would also act to promote downtown in general)
The above act similarly to rail in that your showing through the investment in the "infrastructure" of shelters/stops, signage, unique busses, etc. that your serious about transit. This would help alleviate the desire for more parking downtown and would free up developers from having to put in as much, or any, parking as they would otherwise thus making all types of development downtown more affordable to build, rent and sell. This begins to allow for more true, pedestrian/transit friendly density and begins to bend the parking demand growth curve downward and transit demand growth curve up.
Make sure this circulator route crosses over your other, already identified, future dedicated transit routes, like the the tracks (connected to our new multimodal bridge over the river) to allow for gradual expansion and even possible future upgrades to sections of rail.
This can't work efficiently in isolation. We need to also begin to develop (through zoning and implementation of the Comprehensive Plan) other pedestrian/transit friendly nodes around the city (Cherry Street,Utica Square area, Brookside, Whittier Square area, Pearl District, etc.). This will greatly enhance the urban experience in that your getting far more people within easy walking/biking distance of transit and thus every other district and downtown. One should eventually be able to live in, work in, shop in, visit, any of these areas, including downtown, and be able to quickly get to all the others on readily identifiable routes. What this does is allow for further density in all those areas. A person can live in urban housing of all sorts, that has very little or no parking, for their "accessible world" for shopping, dining, working, play, etc. includes every other area. You increase the number of people in all areas that don't need or use cars as much, and don't need or use parking as much. You also will begin to see other businesses and ideas pop up like shared cars, quick rent cars, etc. Private pedicabs and jitneys will become more common etc.
No more parking garages downtown, instead put in the starter bus route and begin to bend the curve, up on pedestrian/transit friendly growth, and down on car dependent growth.