My rules are:

- fly as far west as you can initially, e.g. DFW, IAH, SAT
- then backtrack east as far as you can, e.g. back to PHL
- routing indirectly via DEN and ORD wherever practical
- then from PHL to the final destination
- balance miles vs time and convenience - don't waste a day for a extra 500 miles
- Great Circle Mapper [link] is cool for comparing and visualising alternatives

I'd do something like:

Day1 - LHR-IAD-SAT
Day2 - SAT-ORD
Day3 - ORD-DEN-PHL-SEA
Day4 - SEA-LAX-HNL/OGG

which would net over 14000 miles - almost double the most direct route via SFO, only a couple of "regional" sectors and only a couple of hotel nights to pay out for.

On the return you could something "easier" like:

Day1 - HNL-PHL-ORD
Day2 - ORD-DEN-LHR

for "only" 11000 miles.

I'm lucky with my TA. I do all the hard work and so long as it autoprices, he's happy.

hth