FYI - to transfer out of USAirways using points.com you need to be a USAirways credit card holder.

If you never had a Diners Club card before make sure that you get an offer which gives the bonus points for getting the card. I do not know what the best offer is currently, but in the past I've seen enrollment offers which offer anywhere from 10,000 to 15,000 airline miles (more if you happen to hit an airline transfer bonus), some of these offers spread the miles over a year and some are lump sum.

Also if you do not have the Starwood Amex, I would recommend getting the card with the 4000 point offer and trying to charge enough to accumulate a total of 20,000 Starwood points which will give you 25000 airline miles. That is far better than some of the conversions you list where you are losing anywhere from 50% to 90% of the intrinsic value of your miles/points.