For the most part, you are correct.
With a Roth IRA, a spouse can name his or her spouse as the beneficiary. Once the spouse dies, the remaining spouse can then roll that IRA into their own. They DO NOT have to take RMDs.
The inheriting spouse can then name a child or children as beneficiaries. If set up properly, once the remaining spouse dies, the children can the split the IRA and take RMDs based on their individual life expectancies.
It is pretty cool concept.
JLP