If each passenger has two rolling suitcases (one full-size and one carry-on), how will you even move around the airport? At SFO after claiming your baggage you will need to take a small train to reach the rental car area, how will the three of you (actually two adults and one small child) wrangle six rolling suitcases over there? It sounds painful.

Except when doing a permanent relocation where you can't avoid having tons of stuff, always be cautious of whether you can physically carry/move all the items you're bringing. I concur with other posters that if you plan to check-in full-size suitcases, ditch the rolling carry-ons for a single small bag with your essential items and documents.