There is a wide range of 401k’s. Many times you can gain access to institutional funds that you would not generally entry into otherwise. You can also gain access to closed funds.
My suggestion is that a 401k is part of a savings strategy. I don’t try and over diversify each retirement account. IE 401 K Roth Ira Investment account. Instead I try to identify the best fund choices I have by aggreagating all options and then diversifying from there.
With respect to 401k’s I am generally positive about them. I think you should always try to max both the 401k an the Roth IRA’s. While there are other psoter who will say that 401K’s are not that great a deal the bottom line is taht even a bad 401K is tough to beath when you weigh in the matching contribution and the deferred tax benefit.
With respect to proper analysis. I would start by looking at the sectors, morningstar ratings, management tenure, 1,3,5,10 performance, management fees, Beta(measure of volititlity and risk) alpha, which give an indication of positive or negative movement in a flat market, and last I would glance over the holdings.
Like a routine checkup I would review you holding twice a year to make adjustments. Put it on a calender today so that you ahve something that gets you to sit down and go through the exercise.
If this is too much work consider the lifestyle funds whick will add a layer of expense but will free you from teh exercise of reviewing this stuff on an ongoing basis.
I would deal with this less except for the fact that I paid a lot of money to go to school and learn this stuff and feel I would be wating that money if I didn’t use some of my education.