Another option would be to get 2 headphones in the 100-150 range that emphasize or do better with different parts of the spectrum. The 350 range is a bit of a grey area because many of the 'phones in that category need amps to sound their best(which puts you well over your 350 budget). of course there are exceptions, but the exceptions are rarely good for all genres, and lets face it, your music tastes cover pretty much everything.
if you want to consider the 2 headphones in the 100-150 range option. I would look into open backed cans (large sound stage as you requested) perhaps the sennheiser hd238's and the audio-technica ad700's would be a good one-two combination. The 238's are good for bass heavy music and the ad700's for pretty much everything else (VERY large sound stage).
There are some good suggestions listed above as well, however I thought I'd throw my 2 cents in with a completley different scenario just to get you thinking