My opinion (and I am sure others think different) is that you should talk to a retirement specialist...
I know Fidelity has some that will come out, but it does make a difference on how much money is in play... the Sub S where I worked had 25 employees and they sent two people and gave us great service... but, we were only looking at 401(k)....
If you go with a FA, make sure that they are not receiving any compensation from the company they recommend, unless they tell you up front... the decisions on which service provider etc. can make a big different in fees... and guess who pays those fees
Edit.... just noticed the previous post... Vanguard is also good, but for 401(k) you need to be pretty big for them to talk to you... I am sure they will talk about the other options...