Cobras TKD and the standard karates are probably tops for all around flexibility. No offense to Cobra, its a great sport, and acrobatically very challanging, but IMO those kinds of kicks are not real world practical, would be lethal if executed ( I use this stuff regularly, and my body takes over when in the mix, so no thanks), and kicking gets you a set of uncomfortably tight bracelets in my state. any of your oldie but goody exercises from your gymnastic days will give you your flexibility back, if thats all you want.
If you have a decent school around, the first few months of judo will condition you the most extensively, for many take downs, falls, rolls, and various limb protecting manuevers.
