Just voting with Christine and Dario: not a good deal, IMHO. Unless you've changed it, this is what you'd scheduled for Rome:
Day 3 Vatican, St. Peter's, Dome, maybe a walk
Day 4 Visit the Colosseum, Forum, Pantheon
Day 5 Heart of Rome walk. Borghese Gallery
You're adding the Capitoline somewhere in there. You are also traveling with a husband and two children ages 12 and 11. While your children would be technically free at the Colosseum/Forum/Pantheon, ALL of you would need a timed-entry reservation for the Colosseum, even if the adults are using the Roma Pass. There's a 2.00€ reservation fee for "free" tickets: children under 18 + Roma Pass holders. I'm only referencing the "ordinary" ticket here. Details are on the coopculture website:
https://www.coopculture.it/en/the-colosseum.cfm
The same applies to the Borghese.
https://galleriaborghese.beniculturali.it/en/visita/info-biglietti/
Your children will not be free at the Capitoline; you'll pay the concessions price for non-residents ages between 6-25 for them. I don't expect long queues at this one but I won't swear to that! :O)
http://www.museicapitolini.org/en/informazioni_pratiche/biglietti_e_videoguide
As well, if you'd planned to use your passes to cover transport within central Rome (transport to/from the airport is not covered), you'd still need to buy tickets or transport passes for your children as they're over the age of 9. So in the end, IMHO, it's really more messing around to try and use the card than to just make your required reservations for ALL of you + pay the fees in advance. The 72-hour pass would also only fully cover base entry fees for the two adults for 2 of the 3 attractions you've listed.