Multiple Roth IRA's

I was wondering if anyone has any insights to having multiple Roth IRAs? I have a 401k through work, a Roth IRA that holds invested mutual funds and I am interested in opening a Vanguard account to invest in a target date index fund. Would the best option be to select a Roth IRA account for the target date index fund or would it be another type of account that would be best? Thanks!