If you are really into low light shooting and print big (really big, especially over 16x20"), then one of the full frame cameras would be the ticket. 6D and 5D Mark III would give you better AF for sports and somewhat better high ISO performance than 5D Mark II, noticeably better high ISO performance than any of the crop cameras. Both 6D and 5DIII focus systems are also able to keep working about 1-1/2 or two EV lower light than 5DII or most other Canon bodies (6D and 5DIII can focus by moonlight, essentially... 5DII, 7D, 60D, 70D can't). 6D has a fairly simple AF system... 11 points with only the center one the "dual axis/cross type". If you are a "center point only" shooter, 6D can work quite well in most any situation. It's peripheral points will be more limited in some situations. 5DIII has a very sophisticated, 61 points AF system, up to 41 of which act as dual axis with most Canon lenses (there are some limitations with certain Canon lenses and some third party lenses.... still the 5DIII's AF is like the 7D's, but on steroids). For sports/action, 5DIII would be superior to 6D, though both can manage it far better than 5DII. 6D is relatively compact and uses SD memory cards. 5DIII is larger/heavier, has 100% viewfinder and has slots for both CF and SD memory. 6D's controls and ergonomics are most similar to 60D. 5DIII is more like 50D, 5DII and especially 7D.
The 5DII is five years and two or three generation old technology now. It's AF system is actually same as the original 5D, so in that particular respect it's around 8 years and maybe three or more generations behind the current tech. Of course, the 5DIII costs more than double what 5DII are selling for used right now, and 6D is a a lot cheaper than 5DIII as well.
Historically full frame cameras have been most ideal for landscapes, cityscapes, portraits... and less ideal for sports/action. This is for several reasons.... One is that the AF systems of crop cameras were typically better designed and performing to follow action. The other is that sports/action generally involves a lot of telephoto work and crop cameras give you "extra reach". Conversely, landscapes/cityscapes tend to use wide lenses and a FF camera lets a wide angle lens truly be wide. But now the lines are more blurred. Today's 6D and 5DIII have much improved AF that's capable of keeping up with sports/action, so FF is not just for more sedate shooting anymore. At the same time, ultrawide lenses for crop sensor cameras have matured nicely while smaller sensor resolution and image quality have steadily improved, both to the point that today's APS-C cameras are quite capable of meeting most peoples' landscape/cityscape needs very well. It's still true, though, that crop cameras "enjoy more reach" with telephotos (i.e., put "more pixels on target"). And, full frame cameras gather more fine detail which can be great for big prints of landscapes, but FF also can require larger, heavier and more expensive lenses to accomplish the same framing as a crop camera. FF cameras also have a bit less selection of lenses, since they can only use FF compatible lenses, while croppers can use both FF compatible and crop-only lenses. (Granted, even limited to "FF compatible only", the Canon system has an excellent selection of lenses, plus there are many FF capable third party lenses).
Ultimately, only you can say which format would be best for you (I use both, for different purposes).
70D and 7D are both crop sensor cameras which will serve well if you don't need to print huge and don't require exceptionally low light shooting capabilities. The 70D is the "latest and greatest", four years and a couple generations newer than 7D. It succeeds the 60D, but inherits a slightly scaled down version of the 7D's fairly sophisticated AF system. 7D is still a fine camera, but is due for replacement fairly soon. I wouldn't be surprised to see a 7D Mark II any time, tho most think it won't happen until 2014. A lot of people think the 7D Mk II will get the new sensor and processor(s) being used in the 70D, so they might be identical in terms of image quality. Likely the 7D Mk II will see other enhancements, but it's anyone's guess what those might be. Canon isn't sharing info. Canon has done away with their APS-H 1D series cameras, which were a third format in between FF and APS-C... I wouldn't be surprised to see the 7D Mk II move more upscale to try to fill that roll even better than the original 7D has, while continuing to use a APS-C size sensor.
Right now, I'd be tempted to get 70D, since 7D Mark II is nothing but speculation and the original 7D is getting a bit long in tooth. Again, only you can say. But if you enjoyed the 60D you had, likely you would be very happy with 70D.
Hope this helps!