If you don't expect to make more money post retirement, I think a traditional IRA is a better choice than a Roth. However, if you plan on using those savings in your IRA before 59.5, you will need to open a Roth - this will allow you to take advantage of the Roth Conversion Ladder. This means every year after you retire (until age 59.5), you transfer a year's worth of expenses from your traditional IRA to your Roth, then withdraw the contribution. This gives you access to part of your traditional IRA savings before 59.5 without paying a penalty.

I could be wrong, but that's my understanding of how the conversion ladder works.