My personal experience (YMMV) is that straight bars give me lots of problems.... wrist pain and numbness. The straight bar position is not at all ergonomical and has been in little general use through the history of cycling. What did help before I changed out to a bar similar to this http://www.universalcycles.com/shopp...&category=2657 (and i use drop bars on my other bike) was to use ergo barends.

I liked the cane creek ergo http://www.jensonusa.com/store/produ...+Bar+Ends.aspx

and lots of people swear by the ergon http://www.jensonusa.com/store/produ...+Bar+Ends.aspx