United is offering:
- 5,000 bonus miles for completing one qualifying roundtrip
- 10,000 bonus miles for completing two qualifying roundtrips
- 25,000 bonus miles for completing three qualifying roundtrips
Ticketing and travel must be between November 10 and January 31, and the first roundtrip must be completed by December 31. Only roundtrips qualify, but it looks like all regular paid fare classes count.