LHR-LAX ?
Really, there is one SFO flight a day but two LAX ones, so for an award seat, LAX is normally easier to secure than SFO.
Many flights to HNL from LAX

LHR-LAS possibly but unlikely
Not easy to secure award seats on this route. However, Hawaiian has a direct flight to HNL (great food and service in First) and LAS is a great stop-over destination - both ways! Both VS and Hawaiian use Terminal 2 which is smaller and less busy than the main Terminal 1. Easier security and faster for bags to appear.

Watch the SFO as a connection to HNL. Most airlines use a horrible 757 on that route. Hawaiian is one of the few airlines that use a wide bodied 767-300. From LAX, you can get a 767-300 on AA or HA which I prefer to a 757 any day.

HA is a Virgin for earning and spending miles but spending on HA is pointless as it is rather pricey given ticket fares