I ride 50/34 x 12-30 on a 10 speed set up. I find it pretty adequate in Colorado. The gaps between gears isn't really noticable. I do have a 12-25 on my heavy wheels I ride on flat days though.
Only occasionally do I wish I had a little lower gear up and a little higher down.
For my area and desire to ride up mountains, I'd stay 50/34 and go 11-32 if I were to go to 12sp.
Two caveats to this. I don't ride my bike loaded. 2 bottles and a seat bag max. A touring set up might need lower gears. The other is that I weigh 140.