Waikato defeated Wellington in the men's final 38-19 while Auckland defeated Manawatu 29-14 in the women's final.
Luke Masirewa was the star for Waikato and picked up player of the tournament.
The top 16 men's provinces and top 10 women's provinces from across New Zealand competed at the tournament.
The Bay women lost two of their star players to injury in the week leading up to the nationals and punched well above their weight to make it to the semis.
Bay women's coach Brad Fleming said his team had done themselves proud.
"The girls showed a lot of heart and I was really proud to see them all get out there and just give it everything they had, especially today [Sunday].
"We had some really hard games and they just fronted up and I think the Bay public saw that we were giving it a crack and got right in behind us."
The Bay women's side finished second in Pool A on Saturday behind Manawatu. They defeated Wellington (19-14), Taranaki (29-7), Canterbury (22-12) and lost to Manawatu (0-19) before beating Counties Manukau 14-12 in the equivalent of a quarter-final to reach the semis yesterday.
Former Rotorua Boys' High School First XV player Mason Walker was a big part of the Bay men's success causing havoc every time he touched the ball with his speed.
The Bay men topped Pool B on Saturday after defeating Canterbury (28-7), Counties Manukau (24-19) and South Canterbury (14-7). They then backed that up with a close win over Northland 17-12 in the quarters.
It was the second year in a row the nationals have been held in Rotorua and a much bigger crowd turned out compared with 2014, with the fans numbering in the thousands.