Retirement Account Juggling - IRA, 401k, Roth

This week I've been re-thinking about our contributions to retirement accounts. Doing this always feels like juggling. There are clear pros and cons to putting $$ into each area.

I generally would just stick extra $$ into my 401k because I like that it is pre-payroll tax so you gain that extra savings immediately. But it isn't possible to just write an extra  $$ to a 401k. It all has to come out from payroll, and in my case I can only change the contribution amount 4 times a year. So not very good for month to month contributions. But I can adjust it to project for 3 month periods.

For those extra $10, $22, or other odd amounts the real only choice is IRA or Roth IRA. Over the course of the year I usually put some $$ into each. I do like the IRA for purposes of reducing that year's income. And of course every one loves the Roth for tax-free growth. That could be huge years, decades, down the road. But there is still something about instant gratification so I think the traditional IRA still has it's place.

I suppose the simplest way to look at this is I diversify my retirement account contributions, just like I diversify said account investments. Do you ever second-guess your retirement account contributions?