The Cityscape is open to all, just turn up and ask one of the hotel doormen to direct you to the lifts. It is actually far better than any of the pictures you see because the view as you walk in along the raised area to the bar has views right around and you are looking down as well as across.
As you say, food is the main expense. We were told that there are more restaurants per head than any other US city and the average life of a new start restaurant is six months. That competition should benefit the customer but in a decent restaurant expect to pay $75-100 for a meal for two with wine or beer. The Bay City Guide has money-off vouchers for many restaurants. Most of the burger-type outlets are very competitive in the $35-50 range for two and the meals are all piled high so you won't starve...
