I was following your post an replies. Neuro and the others gave you a lot of great information to digest. I went to your pics and have to say, they look great.
You have nice lenses, and are getting great shots, you have the basics covered and then some. I am thinking that before you decide on a camera upgrade path, you might want to consider a attitude reevaluation. To get the pics that you refer to earlier, you really need to delve into all of the aspects of photography and its nuances. That also means getting the camera on manual setting and getting comfortable with those settings such that you can get the results you intend, and reproduce them reliably.
You seem to have a natural talent for photography, so really what is daunting is the attitude change. I bet if you commit to small steps, big and great things will happen. After a while, you will get comfortable, and then, you will get a better idea of what your next camera should be.
Just a thought.
you have a nice set of ff lenses that will work very different in practice on a ff camera, are you happy with the lenses you have and how they work for you on the rebel? are you using the 200 a lot or the 100 more? the 35 is going to look a lot wider on the 6d. anyway as i said you have a nice set of fast lenses so i would base my decision on how you like to use them and then go with the format that fits that usage the bestGood advice. My current lenses are pretty perfect at 1.6x. I imagine there'd be a slight adjustment otherwise, with the crop factor most noticed with outdoor sports. The 35 is most everything other than sports with the 100 perfect for most volleyball photography and the 200 perfect for through the net from the other side. I think I have an idea what my ideal camera would be if Canon would be so kind as to allow me to design it, but maybe someone'll beat me to it sometime in 2014. I don't feel the need to shoot overly wide since, even in landscapes, I tend to frame into the most interesting part of the scene and the thought of getting a 300 2.8 to replace the 200 seems daunting. And the rented 100-400 couldn't have been better for the big Alaskan trip.
If you'd like to see, here's my "best of" shots all of which from the T1i except for the 3 from Israel -