Personally i would continue Skytrain to Netwton and than along the rail right of way to Cloverdale and on to Langley. This route is 19.43km long while Falcons is 17.95km long, thats only a 1.48km difference, not significant. This route would be better for White Rock, South Surrey, Cloverdale and their fare grounds, and the King George Corridor including Newton, plus Delta. They can then make a Spur line From Surrey central to Guildford and the highway with a major park and ride facility at the 104th and 160th.
I think this way is better and it only adds 1.48km on to the trip from Langley to Surrey while saving time for lots of other people. It also would add another 3.4km on to a Langley - Guildford trip but that still ok and its again offset with the benefits to other travelers.
edit: it would actually add 8.86km on to the Langley to Guildford trip which is more significant especially if your going to Coquitlam but again it makes that up with South Surrey, Delta travelers.