I just went to the Local taphouse the other day on the way home from work and was very impressed. Only had one beer but enjoyed it immensely and would highly recommend. If you are looking for a feed they also do a five shared dish beer and food matching banquet. $48 a head. Not done it yet so can't comment but I plan to soon. I love the fact that a place like this has opened up in Sydney and plan to contribute to it's hopeful success quite often, especially during footy season.
The Lord Nelson down in the Rocks brews their own as well, not tried it myself but I'm sure others on here have and may be able to comment.
Also one of my favourite pubs in Sydney to have a drink in is The Fortune of War, which down in the Rocks as well. It's just across from the Museum of Contemporary Art near Circular Quay. Not sure why I like drinking here, I just do. Steer clear on nights that they have a small band in the corner though, can be uncomfortably loud and annoying if you wanting a few quiet beers and a chat.
As mentioned, the Macquarie up on Wentworth St brews their own as well, another of my favourite pubs to drink at in the city however I've had mixed experiences with their beers. I reckon you should try them for yourself though.
The James Squire Brewhouse down at King St wharf goes alright too, good beers, decent feed. There's also heaps of other restaurants and bars round there as well which are worth going to. Dress smart though, some like to think they are a little more upmarket and will be a little selective with their door policy on occasion
Last one, I'd doubley vouch for the Opera Bar as well. If and when I ever get vistors from o/s it's one of the first places I take them for a drink. If the weathers good, get there late afternoon when the sun's low in the sky and it's one of the most amazing places to have a drink in any city in the world. They don't miss you for a drink but when you turn around from the bar and take in the view, you won't care.
As for the cab v train debate, I'd advise cab, especially if there's a few of you. It'll work out about the same, if not cheaper, you'll get out where you want to be, no walking from station to hotel, getting lost, etc. If you're looking for a beer after you check in, depending on where you are staying on Pitt St, there is a host of pubs around the traps on Pitt and George. Also, although it is quieter this time of year than any other, and assuming your a normal and reasonably sensible bloke, who will be travelling with the same, I'd resist the urge to go to the Cross on Sat night. If you do get up there, get out by midnight, after that a few heads turn into pumpkins and the lunatic soup well and truly takes over. Ditto with George St around the cinema areas.
Hope this helps mate, it's a good town, plenty of things to do and you'll have a good time