As long as you are fine with the time, and (especially in winter) the risk of missed connections due to weather and equipment issues, go for it.
When I was regularly traveling between LAN and GEG for two years, there were several options. If I was in a hurry, drive down to Detroit and do United on DTW->SFO->GEG. If I was lazy, United on LAN->ORD->SFO->GEG. If I had time, however, I'd rack up miles, usually with ridiculous itineraries on Delta such as (the longest string I remember) LAN->DTW->CVG->ATL->ORD->SLC->GEG