To Max 401k or contribute to Roth

[IdealFugacity]

I can contribute up to 50% of my salary to my 401k, so that's obviously not going to ever happen anytime in the next few decades. So i guess I am really limited by the 15 grand, however thats still edging on a third of my pre-tax income which is pretty high.

Should I save 4k a year to put in Roth IRA (after expenses, 401k to match 50% up to 7%, bonds/other savings)? Or not even use the Roth until I am hitting the federal max for 401k?

I'm thinking, as you guys say, diversification of asset locations, and putting in 3K-4K a year (trying for 4, 3 if saving doesn't work as well in the real world as it does in my excel sheets as i approach graudation) into a Roth would be prudent.

EDIT : Also, I only get an international, large cap blend, and small cap blend index fund through the 401k (there are a couple more choices, but not really worth mentioning), so a Roth would help me diversify into REITs, Large Value and Small Value indexes as well.

Speaking of the fund choices, they are really nice; institutional vanguard funds with like 0.03% ERs, 100 million dollar min. investment. VIIIX, VSCIX, and VIDMX