My favorite league format that one of my leagues uses is the quarter system, with 1 team only eligible to win one quarter. The quarter winners get a $200 bonus for winning a quarter. Then, after all 4 8-week quarters are completed, the 4 quarter winning teams face off against each other for the final 3 weeks, while the remaining teams who didn't win a quarter are bowling strictly for total handicap pins for the final 3 weeks to determine their bonus money for how they finish in the last 3 weeks.
During the 3 week rolloffs, the quarter winners who are bowling against each other are still using the 32 point per night format, and the quarter winner teams are ranked 1 through 4 for the rolloff format. The quarter winning team that wins the rolloff gets a $200 bonus for winning the rolloff, the second place quarter winner gets a $100 bonus, the third place quarter winner gets a $50 bonus, where the fourth place quarter winner gets no bonus money from the rolloff.
The league season is actually split into a 32 week winner, where the teams are ranked from top to bottom based on total points won for the entire first 32 weeks. Then, during the last 3 weeks, the quarter winners are bowling for one bonus prize fund, where the non-quarter winners are bowling for a different prize fund.
Last year, my team (out of 14 teams) finished a whopping 10th place for the first 32 week season, so we got 10th place money for the overall season. However, we did win the 4th quarter, so we got a $200 bonus for winning a quarter. Then, in the final 3 weeks, we came out on top for the rolloff against the other quarter winners, so we collected yet another $200 bonus for the final 3 weeks.
This year, my team (out of 18 teams) finished 5th overall for the first 32 week season, so we got 5th place money for the overall season. We won the second quarter, so we picked up a $200 bonus for that win. In the final 3 week rolloff among the quarter winners, we barely finished in 3rd place, so we collected a $50 bonus for our work in the last 3 weeks.
For those teams not winning a quarter, they collect the prize money for their position after 32 weeks, and they collect a prize fund for their overall performance in the last 3 week rolloff too. The entire league bowls the 35 week season.
Most of the rest of my leagues bowl in half season formats, with the two half winners having a best out of 3 rolloff at the end of the season. I have also bowled in a league before that used the best out of 5 rolloff, so the rolloff night could go the full 5 games if needed (and it often did).