Hi, I'm wondering if you gurus have any suggestions

I need 4K miles left to hit Platinum Medallion. LAX is most convenient, BUR second. I would love to get this done in as little time as possible as I've got small kids and my wife is not too psyched with the idea of me running away somewhere (rather than parenting!) to get to the platinum threshold...

I'm flexible on weekends and weekdays after Christmas. Thoughts?

Thanks in advance, o gurus of flight

PS I thought there was a site that measured cost-per-mile but I can't find it anymore?