I know but I'd only have my 70-200 2.8 and 50mm 1.8 to use on a 5d mkii. I don't think selling my 600d plus 17-55 2.8 and 60 mm 2.8 both efs would raise enough to buy a mk II
with canon you have to make a compromise- with nikon you get the d3 if you're a pro, you get the d3x if you're a studio pro, and you get the d700 if you're anything else, with canon the line is blurrier.
I've never been impressed with the image quality of the current round of crop sensor cameras, I think i'd rather take a 50d over a 60d. So i'd definitely go full frame.
Your options here are limited- the 5d3 is a truly great camera, but it's major $$$, the 5d2 is competitively priced but the AF truly sucks, although if you're doing ok with your 600d you'll know how it works in low light. The original 5d is basically the 5d2 but with a crappier screen, less iso options and a lower megapixel count
so if you want the af of the 5d3, with the resolution of the 5d2, and the price of the 5d , you end up with the 1dsmk2- the least compromised camera out there, for a time it was canon's flagship, nothing taken away, nothing crippled, so for around 800 you get professional AF, full frame, professional body, image quality that destroys the equally priced and overly complicated 7d, the only drawback, is size- weight, and ok so it only goes to iso 3200 which sucks but you can't get everything for under 1k
as you say, the 7d and 60d are the same as your current camera just with better AF and weather sealing- what is it that you actually want to upgrade?
if it was me, i'd get the 5d mk1, the 50mm and 70-200 are really all you need!
keep the 600d and use the 17-55 on it, as on a crop camera it's better than the 24-70 on full frame (you get IS!) and it's not as big or heavy
then you have a portrait machine (70-200 on 5d), and 2 bodies for weddings both with excellent zoom ranges, and a 50mm prime for low light work on the 5d, and portraits on the 7d- it's unbeatable, and the 5d along with the 1dsmk2 are the biggest bargains in photography right now