Wow - that's massively expensive, the Novotel I mean. The plus side is that it's so close you could open the windows and listen clearly to the soundcheck and belt it out while you're in the shower (sing, I mean).
Yes, the Olympic Park station is by far the best. Right next door to the stadium. Trains do go there all the time - just way less of them when there's nothing going on. Concord West is also a relatively short walk. Immediately after the gig, if you hate just getting stuck in massive crowds going nowhere, legging it to Concord West will no doubt take longer than just dealing with the Olympic Park crush, but it might be a nicer, calmer way of getting out.
If you are staying in the city, the coolest way of getting back is via boat. If you've got a group, it might not actually cost that much per person. Good way to end the night if you are an out of towner, plus the band do it, so you never know who you'll bump into on the dock?