As far as the other posts, I do intend for my tax bracket to increase. Right now I'm in the 25% bracket, but even as soon as December I might be moving to the next bracket.
I don't intend for the MMM style retirement, as I like what I do and I definitely would want to keep myself busy :)
I'm a big believer in diversification among investments as well as tax liabilities. Not only could my tax bracket stay the same, but I'm also hedging against tax rates going up down the road, along with means-testing of account balances.
So, my plan is to try and have my balances in my ROTH IRA/ROTH 401(k) accounts be somewhat close in value to my various tax-deferred accounts. That way, just like with having some index funds to have a market-return (instead of swinging for the fences and risking failure), I'm 'guaranteed' to be able to take advantage of whatever tax policies/rates do in the completely unknown future of the political realm - where common sense rarely wins out over various special interests on both sides of the aisle. After you retire (or if you work part-time), if your income happens to be lower one year, you can convert some tax-deferred funds to a ROTH. Conversely, if something crazy happens and they somehow tax ROTH balances, you aren't screwed with having 95% of your retirement accounts in ROTHs.*
Also, because I hope to retire early, I need a heavier balance in my taxable accounts, since the ability to withdraw funds from your 401ks before 55/59.5 is limited to a relatively small SEPP amount.
*While it could seem impossible the gov't would do this, remember that SS benefits were, at one time, only 50% taxable - the theory being that you already paid income taxes on your 50% contribution from your paycheck, while your employer's 50% contribution was untaxed. However, back in the 80s/90s, that changed such that up to 85% of your SS benefits are taxable. So you're getting double-taxed on up to 35% of your SS benefits. And corporate dividends are double taxed at both the corporate level and on the individual level when you receive them. Just like with those examples of double taxation, your ROTH could get hit with a sort of direct tax, or a means-testing indirect tax down the road.