Wouldn't worry about cleaning around the holes - the coils form a good seal.
I switched to the Bosch +4s, and I've been happy.
The Denso iridiums are very good plugs, and will provide performance for longer than any other plug, but you do pay for it. The +4s are spendy at $6 each, but the Densos go for $11 - $15 depending on source.
$100 seems like a lot for a plug change, but with Iridiums you don't need to change them for (supposedly) 100K miles, and it'll run a lot better at the end of that time then with platinums. Or so they say....
It all really hinges on your preference, and how much you want to spend on a spark plug change.
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