In Little Tokyo: Takumi, Sushi Gen, Izayoi and Giggle Giggle (new Korean BBQ in the Weller court)
McCormick's for happy hour (super fried portabello mushroom for $2 or something like that)
I've never been to Water Grill but it is often claimed to be among the best restaurants in the city.
I've been to and recommend:
Kappo Ishito (especially)
Sushi Go 55
Cole's Pacific Electric Buffet [Full bar!]
Clifton's Cafeteria is interesting, inexpensive, and the food is not bad.
shabu shabu house
water grill isn't what it once was, but still serves a mean crabcake
additional votes for sushi go 55 and daikokuya
yang chow (chinatown)
I'm assuming you only want "adventures" and not a list of the old standby's:
626 Reserve - on 626 Spring St. really a wine bar, but suprisingly good food. The neighborhood is definitely an adventure.
re: Liquid Sky
Welcome to the hood! I've been a downtowner for a year, and I too love the Downtown threads.
In the interest of time, here are some previous Downtown threads that might interest you (including one on J's):
...and I posted another one below.
Cafe Pinot has good food if you don't mind splurging. It's absolutely wonderful to sit outside during lunch with the hustle and bustle of downtown, and it's romantic at night.
Fire Engine No. 28 has good food that isn't cheap either. Traditional interior but not stuffy, relaxing atmosphere. Food is American fare.
Ciudad has a very fun hip interior. Food is okay -- all kinds of latin food, except Mexican I believe. They used to have this halibut soup dish that I loved but for some reason they stopped making it. Good desserts.
I just had lunch at R23. It had been a couple years probably since I had been there. The place still rocks. It isn't an everyday kinda place. But if you do one of the lunch specials like fried oysters you can keep the damage to a minimum. Though if you're with a group, it's hard to resist the stunning ceramic platters of sushi. Reservations recommended. Cool loft style space. Service, while well intentioned, can be elusive. I finally got up and asked the manager for our check. Divine special dungeness crab salad. $21 however but there was lots of crab. Yummmmm!
Gotta recommend Ocean Seafood as well. The menu is immense, the place alittle too brightly lit for my taste, but the scrambled egg and shrimp is good as any you''ll find in the San Gabriel Valley. Had about twenty items over the years, never disappointed. They do a great take-out as well. It's off Hill (you can get to it from Broadway as well), a couple of blocks up from Chavez/Sunset Blvd.
Here's a recent thread that might help: http://www.chowhound.com/topics/407759
Since your priority is adventure, I would recommend Blue Velvet. It definitely has its detractors (on this site and I'm sure elsewhere), but I had a really good, interesting meal there, it has great decor, it's a completely unexpected location, and it has a skyline view of Staples (which is actually kind of beautiful from that vantage point). It's fun!
Adventure would be trying to find R-23 for the first time; trying to get into Sushi Gen anytime; a cup from the $11,000 machine at Groundwork; talking to Monica at Banquette Cafe; a visit to Grand Central Market before 6; knocking back some whiskey at Seven Grand; some fun at the Brothel; deciding on your favorite downtown King Taco. Had enough?