Read through this thread. My most recent entries (post No. 19 & 20) covers the winter sky:
http://www.iceinspace.com.au/forum/s...d.php?t=174236
I have been able to see the arms of M83 in my 8" dobbie. The key here is not just a dark sky, but a very transparent one too. The Sombrero is very easy too - I've seen it in a 30mm finder.
Alex.