I'd say consult with the schools, youth groups, probation and so on as these groups are likely to be a serious 'base load' of turnover; best you get the numbers through the door and make it work then pander to the views of a very small number of climbers and f--k off the schools @ etc
Outside Sheffield / London most walls, other than schools & etc will probably be virtually empty and making a loss between 11:00 and 18:00.
Focus on the punters and getting the stuff right for the climbers should be easy. See the worst climbing wall thread for ideas of what not to do.
