I really like the flexibility of using CO DL and NW for my domestic flights. Between the three, they have the right combinations of schedule and fares which is great. Lots of free automatic upgrades especially on NW metal, occasionally on CO, and of course none on DL (yet). Granted the quality may not be as good as AA but then, really I can about the seat and leg room and well the price is certainly right.

Getting to India, you have lots of options, CO directly, NW and KLM via AMS, and well overall very happy with Skyteam.