So, does anyone know of any good foss calendar that has better notifications than the stock google one?

I'd like to be able to add notifications at/before the event AND notifications at/before the end of the event.

Scenario: Child has a bday party at friend's house.

I want to be able to set the activity's length, say 2hrs. Set a notification before the event to remind me when I need to leave to drop them off, and set a notification before the end to go pick them up.

I think it's annoying to have to create a second event to remind me to pick them up. and with multiple children and events the calendar gets cluttered with duplicates.

Suggestions?