Stop building bleachers and get you Lower Tier up to 4000....after you promote, slowly take your courtside up and then when you egt to Div. 1, take your Lux. Boxes up to 50. If I could do it over I would build an arena that looks like this..
My arena now....
Bleachers :  17417  
 Lower Tier :  4696  
 Courtside Seats :  500  
 Luxury Boxes :  50
Total Capacity :  22663  
What I wish it looked like....
Bleachers :  16000
 Lower Tier :   6000
 Courtside Seats :  500  
 Luxury Boxes :  50
Total Capacity :  22550