You can't do a stopover both directions, but you can route through the same city coming back. You don't say when you want to travel, but I just tried out the SFO->HKG->TPE->SFO routing on united.com using multiple destinations and award travel, and found a bunch of options. And it was 65K per person. Most of the legs were two flights, changing in SIN or BKK or NRT. I saw options for Saver Economy on UA, SQ, NH, OZ, and TG for various legs.

joe