I'm looking to go to NYC to Spain roundtrip for me and my wife in September/October 2013 and can be flexible in my travel dates. Planning on going for a week/maybe a little bit more and am indifferent between flying into Madrid/Barcelona or any other major Spanish airport serviced by the NYC area. Would like to fly round trip business if possible but would do economy both ways if it was a much better deal. Also do not mind paying cash and then upgrading with points if there is a good deal to be had.

I have 100k ultimate rewards points, 50k membership rewards points, 70k united points, 25k delta points, and 125k starwood. I would be willing to do a credit card sign-up to get extra points.

I saw the avios conversion bonus at Amex but know that a lot of those redemption come with hefty fees. What airlines are my best bet to look at/best day of week for the tickets? Any tips/tricks you can recommend for this type of redemption?

Thank you so much for your help.