Now, you have to think about how you can salvage this well planned trip. First, be willing to look at the landscape and take photos anyway. Start looking intimately at the landscape. Is there a small grove of trees semi obscured? What about the macro opportunities. Look everywhere for something you may have missed had the conditions been as planned.
Try to have a back up location as well. We all know that direct light is only good for 30min before and 45min after sunrise. I always have a second location picked out (when possible) to photograph after the landscape light is gone. Usually it is under a canopy of trees going for a closer view of the forest (or environment). This can work because if the primary location turns out to be a bust you can move to your secondary location early.
I hope this helps you plan your next photo trip!