I'd run with this
Warner
Cowan
Lock and load these two, they haven't really had that big opening stanza yet this summer, but they compliment each other really well, and I don't like change for the sake of change. Warner may never be as consistent as we want, but like a Jayasuria, sehwag or McCullum, he can pop a teams bubble very quickly and can take a game away from you before you know it. Cowan is pretty much the perfect foil, he's got an interesting technique, but he makes it work for him, and loves the scrap (something you can't really say about the rest of the top 7)
Doolan
Clarke
Hussey
Watson
Wade
I think the selectors will pick Hughes (which I'm fine with to be honest) but I'd go doolan here for a number of reasons.
He's in ripping form (so is Hughes).
Right handed bat (pick Hughes and you get 5 lefties in the top 7, which is pretty ridiculous).
He's a natural no. 3 (to be honest it's not a big deal, but if you add Hughes to the mix you then have essentially 4 opening bats)
The other big change in there is Watson to 6, which I think maximizes his potential as a bowler (when he builds some fitness) and also as a batsmen. For me he hasn't found a method for the top order in test matches, it's all well and good for the one day game, but even when he was in form, I think he still struggles with picking his spots and pacing his innings. Add to that what Ian Chappell said about his modes of dismissal and I think there's also a minor technical issue there also (he does tend to lunge forward a lot). I think he'd benefit hugely from the older ball, and he plays spin decently well as well which is always a quality you want in your no. 6.
Siddle
Cutting
Starc
Lyon
Siddle is a no brainer, starc was our best player in Perth, and Lyon is esconsed so there's one spot there up for grabs.
The selectors could stick with Johnson, but frankly I didn't think he deserved to play in Perth, and this is the 11 blokes I think can do the job in Hobart.
Therefore I've gone with Cutting here, he's bowling (and batting) very well at the moment, he's aggressive, and I reckon he (along with starc) he could really unsettle the Sri Lankans with some short stuff.
Not relevant to this test, but this time next year I hope guys like Burns, Maddinson, Keath, McDermott, Faulkner and Patterson are really starting to kick the door down, and guys like Hughes, Henriques, Bird, hazlewood and Cummins can continue to put up big numbers.
Apologies for what ended up being fairly rant-ish