Gore would have likely been re-elected in 2004. And there is no way Captain 0 would have been elected in 2008. The Ds would have nominated a Clinton/Gore crony, or John Edwards would have been at the top of the ticket, as Gore's VP.
Of course, we can only speculate, but considering where we are now, I'd take my chances with Gore winning and having a do-over.
Yes, it is only speculation, but things would even be worse today had Gore been elected in 2008. For one thing, there might have been even more Islamic terrorist activity around the world and more in the US after 9/11. Saddam Hussein would still be in power in Iraq and very likely control a good part of the Middle East. Gas prices might be at European levels, and the US even more dependent on foreign oil due to the rise of environmental wackoism in a Gore Administration. And the size and scope of the federal government would be even larger. Some form of socialized medicine may have been firmly implanted already.
I don't necessarily buy your thought that two terms of Gore would have ruled out Zero in '08, but the logical 'Rat successor to Gore would most likely have been none other than Her Royal Thighness, Hillary Rodham Clinton.