Wolf has a lot of good points, but let me address it from my personal experience, having "recently" retired.
I had done forced investing for years with negative cash flow real estate. In '96 I got my first job with a 401k with company match. Was broke, so I started at only 5% with a 4% company match. Figured my tiny military retirement (ahem, divorce involved) and Social Security, along with rental income from real estate would fund a nice retirement. Only contributed to a 401k to get the match and figured it would be my "pin" money. Travel, tools, hobby car, that kind of stuff.
Over 20 years, as my pay increased, my 401k contributions increased to 10%, then, in the two or three years before retirement to the max allowed, with catchup.
Fast forward to retirement 5 years ago. My 401k (rolled to an ordinary IRA) went from Corvette and cruise money to real money. No longer just pin money I couldn't just stash it and ignore it. Started rolling about $40k-$50k a year into a Roth, but the gains are such the IRA hasn't gone down.
What the financial planners don't tell you is that with average gains (say an S&P 500 index fund) your 401k/IRA will be a multiple of your contributions over your career and during retirement. Even though you get to deduct your contributions and save a few tax bucks during your working years, the fact that 100% of those contributions and (here is the rub) 100% of the gains are taxed as ordinary income upon withdrawal means that you are going to pay a lot in taxes. If the money was in a Roth, only the contributions would have been taxed, and the gains are 100% tax free.
Regardless of your tax bracket before and after retirement, and regardless of what the future holds for increased taxes, put everything into a Roth IRA after contributing enough into the ordinary 401k to get the company match. If your company offers a Roth 401k you can contribute to and still get the match, even better.
The only two cases this strategy doesn't work is if you park your 401k money and won't have gains, or if you are close to retirement and plan on depleting your retirement accounts shortly thereafter.