Perimeter seating changes the night, not just the capacity
In a stretch limousine the group is in a line and the people at the ends spend the night talking to whoever is beside them. In a party bus the seating runs around the perimeter and everybody can see everybody, which is why it works better for a group that came out to be together rather than to get somewhere. There is room to stand and move between stops. If the evening is the point - a birthday, a bachelorette party, a group going to a concert - this is a different product from a limousine, not a bigger one.
Where it is going matters as much as who is in it
A party bus is a large vehicle and the venues at the end of the night have their own published rules about where one may stop. The Hollywood Bowl directs cars to Lot C at 6655 Odin Street, entered from northbound Highland Avenue or westbound Odin Street. The Rose Bowl does not permit drop-offs at the stadium at all on game day, and its bus and limousine passes are advance-purchase only. Dodger Stadium routes car services in through Sunset Gate A to drop in Lot 11. Name the venue and the date when you book and the arrival gets planned around what the venue actually allows.
Hourly, a realistic end time, and where the night finishes
Buses start at $249 per hour with hourly minimums, and continuous service carries a three-hour minimum Monday to Thursday - which is the right shape for this vehicle anyway, because sending it away and calling it back defeats the point. The two things that most change the quote are the total time from first pickup to final drop-off and where the night ends. A loop that finishes where it started prices differently from one that ends over the grade or down in the basin. Give a realistic end time; these nights run long far more often than they run short.