Rolling over the 401(k) to a separate "rollover" IRA (an ordinary traditional IR that has simply been funded with nothing other than the rollover from the 401(k)) can allow the funds to be traced back to the 401(k) for creditor-protection reasons. Commingling the rollover with funds from other sources such as ordinary contributions might disallow such tracing back. Different states and the federal government have differing rules for this. If you are concerned about creditor protection, the creditor protections afforded when the account is maintained as a rollover account would be no less than those afforded in the case where the funds are commingled with other funds and could be better.
