The 15K promo is valid only through the end of 2005. There's no way to know if anything like that will be available in the Spring of 2007. A regular 25K saver award LAX-LAS-LAX (or SFO-LAS-LAX) does look like a waste of miles for such a cheap flight and short distance.
Btw, HNL-SFO/LAX-HNL would be only 35K, not 35K x 2.