I need to book a round trip award ticket from PHL>SFO for some time in July- trouble is I'll be escorting a group of high school students from SFO to ULN and am waiting on the company I'm working for to tell me what time I need to be at SFO before departure, and when I'll be free to leave afterwards. The flights I've been looking at are already at "medium" award cost at 40K miles, and I can just barely cover that, so I'm wondering, what determines when award costs go up? I am looking at July 8th PHL >SFO and red-eye July 25th SFO>PHL but don't want to book until I get the go-ahead for that red-eye. Will costs go up tomorrow because I'll be 1 month from travel date? Any insight would be VERY much appreciated.