Having flown several times Denver to India I really like UA/LH combination as well. Either through FRA or MUC works as LH has expanded their flights from MUC to India as Munich is a big tech town and does a lot of tech exchange with India.

I do find that AA/CO/DL have better fares sometimes, UA is always competitive.

Sometimes going the Asia way on Star Alliance can work as well. A good friend of mine here in Denver does that regularly gaining more miles but it does take longer.

The 50% miles on CO/DL don't appeal to me at all.