Look into pricing and schedules on OZ - I don't know what their schedule to SEA is lately but they do ICN-DEL on a 777. I have taken that flight and especially from SEA it would be the fastest route to DEL for you.
You could also do SEA-NRT-ICN on UA and overnight in ICN if you choose; I don't think that routing would get you there in time for the ICN-DEL flight which I believe leaves around 8:00pm.
Another cost-effective option could be EVA via TPE in either Elite or Premium Laurel class - I think the onward segment would have to be on CI though, as BR do not serve DEL AFAIK. Good luck.
If wanting to go via ICN, you could also take UA n/s from SFO that gets in around 6 pm (as long as SFO doesn't have "weather").