Can you be more specific with your digestive desires? Vancouver has so many places, how much do you want to spend, where will you be staying etc... I can suggest the usual suspects, Vijs, Tojos (who I do think serves up some really good sushi notwithstanding a few other posts) but they not be what you are looking for.
In that case I would say that seafood is what this area is known for.
With that said: For Dim Sum I dont think you can go far wrong with Pink Pearl, Sun Sui Wah is internationally renowned for great seafood. Rodneys in Yaletown serves up some of the best Oysters in town, "C" is one of the best fine dining seafood restaurants in town although it is $$$.
JWh, where is GUU?
The best Guu is Guu W/ Garlic and they are located on Robson/Bidwell (end of robson near Denman, kiddy corner to McDonalds). There is also another location in Gas Town (on Water Stree, near sea bus terminal/steamworks) and the third location is on Thurlow street (just of of Robson behind Banana Republic)
By far the best one is Guu W/ Garlic. They have a menu that anyone can eat off of, the service is great, and the atmosphere is fun. My advice, go early as they line up from 5:30 on. They are open late till 1am, but are steady busy until then.
Some menu highlights are: Chicken Karrage, Tuna Tataki, Grilled Yellow Tail, any of the dail special and the Almond tofu for dessert!
The Observatory at the top of Grouse Mountain on the North Shore for fine dining.
You take a spectacular cable car ride up to the summit. The dining room has a panoramic view of the harbor, the islands and the cruise ships when they're going out so make a reservation for a window table and ask them to recommend when you'll get to enjoy the sunset. The food, meanwhile, is also wonderful. Really first rate.
If you want to make a day of it you can head up early and stop at the Capilano Suspension Bridge for the afternoon. There are pleasant well-tended hiking trails that you can walk even in comfortable shoes and nice slacks (not heels but not necessarily sneaks either). And a few years ago they added a "trail" that goes up 60' or higher into the canopy of the huge firs (I keep a slide show of that as my computer wallpaper). If you want something uniquely Vancouver, that would be high on my list. Then you could drive the rest of the way up the hill to the cable car and have a lovely dinner. (PS: don't be dismayed by the folks on the cable car who have been hiking and biking serious terrain all day [you'll know who they are immediately!]; the mountain has lots of other activities besides dining.)
I, personally, also always enjoy fried oysters at Troll's in Horseshoe Bay. It's just a coffee shop but it's a popular and a pleasant one and I love to sit over lunch and watch the ferries come in and go out. For me, that's quintessential Vancouver and always will be.
Oh, I also love a walk around the harbor downtown. There's a restaurant called Cardero's (at the foot of Cardero). It's situated out into the slips where you can watch some of the major yatchage, kayakers and even float planes coming in and going out. It's great for lunch or for supper and you can feel very comfortable walking around the water and all the surrounding areas until late, late into the evening. If you feel like it you can stroll up to where the passenger liners are moored or go the other way into Stanley Park or around the small lake on Georgia. They're all lovely walks.