Centuries from Rodney's Jamie White and Onerahi Central's Pieter Lambrechts have booked the teams a date with each other in the Greg Guy Shield final.
Rodney easily accounted for Mid Western while Onerahi had a comprehensive victory over Whangarei Boys' High School.
Batting first, Rodney raced out to a great start as the likes of Ben Clarke (68) and Jordan Kose (30) gave strong contributions against a struggling Mid Western attack.
But it was the 140 from White that stole the show as he found the fence with consummate ease.
White led Rodney to 298 for 6 from their 40 overs, leaving a big chase for Mid Western.
The target proved to be too much for Mid Western who stumbled to be 117 all out, Nathan Condon's 33 being the best of the bunch.
Their final opponents Onerahi looked in imperious touch as well as they picked up a 152-run win over WBHS.
Onerahi were impressive with the bat as top-order batsman Stephen Guy (31) and Robert Lee (41) got them off to a solid start.
But it was the classy ton from Lambrechts that put WBHS to the sword. The unbeaten 109 featured some enterprising shots.
Richard Stobart (2 for 22) was the pick of the bowlers as Onerahi made 257 for 7.
WBHS struggled to assert themselves with the bat as opening bowler Axel Sheppard (3 for 17) and Kirk Henderson (3 for 14) limited them to just 105.
In other results, Kamo High School grabbed a 42-run win over Kerikeri after a good all-round performance from Max Turner.
Turner picked up 63 with the bat as he and Nathan Parkes (63) helped them set a total of 237 for 6. Lovepreet Singh picked up three wickets for Kerikeri.
Kerikeri gave the chase a good nudge with good innings from Kirish Patel (59) and Owen Arthur (46) but two wickets from Max Turner and a good showing from Zak Chapman (3 for 35).
The other match saw Kamo beat City in a high-scoring affair.
Logan Choat (90) and Jacob Cherrington (89) dominated the scoring as Kamo put on 289, with Richard Cates contributing 42.
City tried valiantly as Tim King (65) and Bruce Kessell (47) put on good totals. However, a tight spell from Sean Daniels (4 for 14) ended City's reply at 178.