I've been working to max out the TDA (pre tax) in the 7% fixed and the 457 ROTH to the max with the Equity Index, Mid Cap Index, and some International. The Equity Index has the lowest cost of any of the choices in the 457, so I try to look at my investments globally to achieve the right mix. Since the International and other offerings are partially actively managed (many with lower than index returns for several benchmark periods) I avoid them.
I sure wish the TDA could be ROTH, but clearly that isn't possible. I too am in the 25/55 program, but don't actually want/think it will be possible to make it that long. I've been religious about saving in ROTH vehicles so I can access funds without penalty when I leave to support myself for the first many years.
The 457 has a "investor directed" account you can access though TD Ameritrade. It looks as though this is a way to access lower cost (index) funds for International or other asset classes, but there are restrictions. I've set up the account, but haven't diverted any funds at this point. The NYS 457 is actually a much better beast than the NYC one, but as a NYC teacher I can't access it. They have less fees and less restrictions on the "investor directed" options.
If you're having a hard time filling the buckets and have after tax funds, I would consider living off of these funds as you load your accounts to the max. I was able to do this last year and had some pay periods with literally change as my NET pay.