If you want to allow parent viewing, it should be seperated by a wall to the gym (so what is said in the parent area can't be heard in the gym and vice versa) and be through windows or a video monitor. I can see pros and cons of parent viewing, but that's for another thread ;). If people are driving long distances to come to your gym, you want to have a parent waiting area even if it can't see into the gym - ideally that waiting area will have wifi (so parents can work if they want and siblings can do homework, etc.), air conditioning and comfortable seating.
Equipment-wise you need a spring floor, a tumble track to a resi, and extremely high ceilings for basket tosses. A pit is ideal, but I don't think it's an absolute necessity - especially if the gym isn't the type w/ multiple level 5+ worlds teams.
Reliable vending machines w/ a decent selection of healthier snacks and drinks would be wonderful! As would a TV in the parent area. These two things are just a bonus.