I have used
http://www.worldclassperks.com/ 3 times in the past month for 2 future vacation trips and one trip for my friends - total of 9 tickets and their service was fantastic. I'm not a big miles junkie but understand the value. We were provided multiple options, cabin layouts, difference between first and business pricing and how first class for our Asia trip was better (have a boat load of United mies). Our 2 trips were booked within 24 hours and our friends within a few days as they were exploring additional destinations.