Foodefish,
You probably know this, but I'd say max out 401k contributions at the 20k level even if it means using other taxable savings to live off, since the goal is to get as much of your saving into tax advantaged vehicles as possible.
Later, when you retire or ER, you can take advantage of your lower income and tax brackets to convert some of the eventually taxable regular IRA/401k funds into Roths, should you wish to.
Don't forget, you can make a contribution to a Roth IRA in addition to your 401k each year, assuming you meet the income requirements.
And see if your employer offers a Roth 401k -- it is new but some do offer it. Basically it lets you get the bigger 401k contributions straight into Roths.