Both those thrones work great for 4" figures. I have both. The GoT one is VERY fragile and the tips of the swords break very easily. I broke almost all of mine when we moved.
There is also some good thrones in the Imaginext line. They will need some painting and some work to make them a good Cobra Commander throne though.
Its not as huge as those other 2.
There is also the Shao Kahn throne. [ame="http://www.amazon.com/Throne-Mortal-Kombat-Exclusive-Action/dp/B007Z7QZK0"]Amazon.com: Shao Kahn Throne and Arena with Shao Kahn Mortal Kombat Exclusive Action Figure: Toys & Games@@AMEPARAM@@http://ecx.images-amazon.com/images/I/51%2B-69%2BDCSL.@@AMEPARAM@@51%2B-69%2BDCSL[/ame]
The Chap Mei Viking ship also comes with a nice throne. This one might be a challenge to get here in the US though.
The new Castle Grayskull also comes with a throne. This one is a little big for 4" figures but Cobra Commander does have an ego problem...