I think most people on here will tell you to steer clear of points.com if at all possible.

I have no tips about points.com, but those united/continental miles can be transferred to Amtrak Guest Rewards, where 10,000 miles gets you $100 gift certificates to lots of places. So 400,000 miles would be $4,000 to places like Barnes & Noble, CVS, Applebees, AMC or Regal movie theaters, etc.

To transfer out of Amtrak you need to have select membership or an Amtrak credit card (with $200 Amtrak spending that year). But anyone can transfer in, and I don't think there are limits on the number of miles you can transfer. I could be wrong about that though, you could call and ask.