[taken from an email to Yee and to be further edited later]
So you're going to Sydney. YAY! I love Sydney because it's like the best of California but with public transit that actually works.
Of course, there are the classic touristy things to do. The first thing you should do (esp if it's not dumping rain) is to go to the Opera House and the Royal Botanical Gardens. They're right next to the CBD and you just can't miss 'em. Lovely walks all around that area. If you don't mind spending a little money (and maybe having to make reservations), the Opera House tour is really fascinating. There are also free docent-led tours of the Botanical Gardens; so if you wanna learn more history and botany (rather than just seeing pretty views and plants), call ahead and find out the times for those free walks.
But what I love most about Sydney is the extensive network of coastal trails. They've really done an amazing job re-shaping the harbor and coastline into an accessible resource for everyone. I think that walking in coastal Sydney is perhaps one of my favorite things to do in the whole world, so you'll forgive me for going on a little long about it.
Both the Lonely Planet Sydney book and this site:
http://www.walkingcoastalsydney.com.au/
have great maps/descriptions of the various walks and points to note during your trek.
The absolute must-do walk is from Bondi Beach down to Coogee Beach, but I recommend continuing the trail all the way to Maroubra, which is a wonderful beach for getting away from city bustle. And you get a fun section of "trail" that's just sandstone right at the water (at Lurline Bay). Convenientlly, you can get back to the CBD (central business district -- the center of Sydney) via a bus (or bus-train combo) from any of these eastern beaches! So faboo, especially after Houston. ;^)
The second absolute must-walk is across the Harbor Bridge to Milsons Pt., then through Kirribilli, Neutral Bay, Shell Cove, Cremorne Point, and little Sirius Cove to Taronga Zoo. The Cremorne Point reserve is so ridiculously beautiful for mixtures of landscaping, a bit of wild scrubbiness, the Opera House & bridge views, and absurdly posh houses.
I also loved the walk from Taronga Zoo to Middle Head, but it's not that different from the Cremorne Point part, so you might not feel the need to do both.
The third must-walk is The Spit to Manly. This one's a bit longer, but it is so, so pretty. We planned to take a whole day doing it, which left plenty of time for exploring the coves, swimming, & taking lots of photos. And you end up in Manly, which is one of those tourist destinations everyone has to go to at some point, either for the beach itself or to watch the surfers. And you can take the ferry from Manly back to the City, which is the cheapest harbor cruise you can buy! =^)
If you just take the ferry to Manly, then you should definitely do the Manly Beach to Shelly Beach to North Head loop walk -- the views are stunning and there's military history stuff to look at too. This map has both the Spit to Manly and North Head paths on it:
http://www.walkingcoastalsydney.com.au/brochures/documents/ManlyLagoontoNorthHeadMap.pdf
Ok, that's probably enough about walking.
In the city itself, there's a fun chinatown area with kickass dimsum (if Houston has left your palette a little sad...). We like East Ocean Seafood Restaurant on...Sussex I think. (One entrance on Dixon, one on Sussex.) There's not a lot of pearl milk tea in Sydney yet, but the main place is called EasyWay and offers "half sugar" as one of the standard options. Hooray. ;^) Other fun neighborhoods for wandering are Newtown (the Berkeley of Sydney, complete with "Nuclear Free Zone" sign), Surrey Hills, Paddington, and Darlinghurst -- a bit posh, but fun. If you need to buy souvenirs/gifts for people, the one-stop-get-'er-done venue is the Rocks Markets on weekends; you can seriously do any or all gift shopping you need to do in under an hour there. But buy carefully -- most of the items you can buy there are from local artists, but watch out for generic crap made in china in between the good stuff.
I don't have a lot to say about museums in Sydney, because I spend the vast majority of my time there outside & walking. But the contemporary art museum is pretty rockin', and the Observatory (right at the base of the harbor bridge) is fun too. The Powerhouse Museum is supposedly exciting and Exploratorium-like, but I've yet to go. Also, it's worth going inside the QVB just to get a look at it, even if the shops are not to your taste -- it's impressively preserved, considering all the crazy built-up CBD-ness around it.
Our favorite restaurants are posted here: http://lavendrome.net/blog/?p=29 (or try this http://174.62.72.181/blog/?p=29), although we seem to have left Harry's Pies off the list. Harry's Pies really are the best to-go savory pies you'll get anywhere; not too mushy, not too salty, not too tough/chewy. Try the tiger (with the pea mash) for a true Oz meal experience. For a treat, Rise's half-price omakase menu (Tu, Wed, Sun) and Gelato Messina (oh gawd so good) are not to be missed. Seriously. Same for Hominy Bakery if you go to Katoomba.
Speaking of Katoomba -- another 'must do" for any trip to Sydney is a day trip to the Blue Mountains. You can take the train to Katoomba, grab some packable food from Hominy Bakery, and then go on the Giants Staircase (Giant's causeway?) hike from Echo Point and The Three Sisters, halfway down into the valley, and then back up again. Or if you don't want to have to do the back up part, you can walk away from the Three Sisters (to the right if you started facing them) and enjoy a high-cliff-edge walk, then go down into the valley near Katoomba Falls, then take the hilarious Scenic Railway back up. It's basically an old mining funicular turned into a tourist attraction. Worth doing once if you enjoy an occasional spot 'o cheese on your vacation.
Other random things to do:
Here are some generic travel and packing tips I wrote up before (well, for the warmer times of year at least):