Thank you all! This is very helpful.

I will call BA and see if they can find Alaska airlines tickets for my dates.

There are no seats on United for 25K round trip. The only ones available are 50K each way on first class.

Regarding MR transfer to SPG to Alaska Miles: I'd need 40K*2 Alaska miles for two of us, which will be 65K MR (since you get a bonus of 5K for every 20K SPG transfer). So, I thought its not a terrible deal.