Currently I'm thinking of just doing the short trip, Wednesday the 25th to either Tuesday the 31st or Wednesday the 1st (probably the later).
Why? Well, I went shopping last night with ozisim and gomino who are up visiting from Sydney. The discussion went to a lot of strange topics, including Mardi Gras, and there looks to be a fairly good chance that I will be going to Sydney in February/March next year to go to Mardi Gras.
I've wanted to go to Mardi Gras for a while, so this looks like it could be a lot of fun! :)
Edit: I've just booked the flights. Wednesday 25 Jan, 12:05 to 15:20 on Virgin Blue flight 324 and Wednesday 1 Feb 14:00 to 15:05 on Virgin Blue flight 323 for a total of $202. The joys of daylight savings. The flight down is "three hours", while the flight back is "only an hour".