That is a pretty general question. I cannot make a recommendation withough understand more about your firm's structure and the goals for your participants. There are many options for smaler plans to set up a 401k . It is also possible to set up multiple plans in order to meet your objectives (i.e. 401k with a profit sharing plan and/or a defined benefit plan.
As for are allowing individual brokerage accounts. There is an option called a "brokerage window" that allows participants to select investmnet options in a brokerage account style account.
I hope this helps a little. Please contact me at 908-821-9764 if you would like to discuss your firm's objectives for a retirement plan(s) in more detail.