I know this is an elementary post for many, but I'd appreciate any help.

I'm trying to plan a ~3 week round trip flight from BOS to LAX any time from June 20th to the end of the month. I have a plethora of Amex and UR points, about 10k AA, and 50k US Air miles. Best time to leave / return? Is it worth utilizing points for ticket purchase? Possible to upgrade to Business without spending a fortune? Thanks.