If my calculations are correct Diners Club points can be transferred to 36 airline programs once you allow for transfers via Starwood.
So my current DC points balance of 120K could be converted to any of the following (including Starwood bonus for transfers of 20K):
75,000 Aeroplan/Air Canada via Starwood
75,000 Air Berlin via Starwood
75,000 Air China Companion via Starwood
1,154 Air New Zealand & Air Points via Starwood
75,000 Alaska Airlines Mileage Plan via Starwood
75,000 Alitalia MilleMiglia via Starwood
75,000 All Nippon Airways (ANA) Mileage Club via Starwood
75,000 American Airlines Aadvantage via Starwood
75,000 Asia Miles via Starwood
75,000 Asiana Airlines via Starwood
75,000 British Airways Executive Club via Starwood
75,000 China Eastern Airlines via Starwood
75,000 China Southern Airlines’ Sky Pearl Club via Starwood
75,000 Delta Air Lines SkyMiles via Starwood
1,000 EL AL Israel Airlines - Matmid Club
75,000 Emirates Skywards via Starwood
75,000 Etihad Airways via Starwood
75,000 Flying Blue via Starwood
30,000 Frontier Airlines -*EarlyReturns
75,000 Hawaiian Airlines via Starwood
75,000 Japan Airlines (JAL) Mileage Bank via Starwood
60,000 Korean Air - Skypass
150,000 LAN LANPASS via Starwood
75,000 Miles and More via Starwood
75,000 Qatar Airways via Starwood
30,000 SAS (Scandinavian Airlines) - EuroBonus Points*
75,000 Saudi Arabian Airlines Alfursan via Starwood
75,000 Singapore Airlines KrisFlyer via Starwood
60,000 South African Airlines - Voyager
30,000 Southwest Airlines - Rapid Rewards
75,000 Thai Airways International Royal Orchid Plus via Starwood
37,500 United Mileage Plus via Starwood
75,000 US Airways Dividend Miles via Starwood
37,500 VARIG Smiles via Starwood
120,000 Velocity
75,000 Virgin Atlantic Flying Club via Starwood
Alternatively 120K DC points would get me the following hotel points:
118,800 Best Western Rewards (plus a few DC points left over)
120,000 Choice Hotels - Privileges Points
150,000 Hilton Honours via Starwood to Hawaiian Air or Virgin Atlantic
60,000 Hyatt Gold Passport
60,000 IHG | Priority Club*Rewards
60,000 Marriott Rewards
60,000 Starwood Preferred Guest
Now to work out which would be best for me. Might be a long job as half of these I have never heard of!