First time to go to Key West
I agree with all the responses so far, especially breakfast at Blue Heaven, still one of my favorite things to do after living here three years! Island Dogs on Front St. is a good late- night bar with lots of locals. Ambrosia is #1 for sushi, Jack Flats for burger, beer, catch up on sports in the real world, Virgilio's for martini's and late-night live music, Michael's (I prefer to sit at the bar) for dinner. Hope this helps a little.
I know there are other threads on Key West, but who can resist?
Breakfast at Blue Heaven is just that.... Make sure that you get the banana bread- I thought it was a gimmick, until I tasted it. It is sliced think and has a velvety texture with really good fruitiness. Dinner is good there too, but I find that it's an even better place to feed a hangover....
The fish tacos at the Schooner Warf bar (near Elizabeth St., by the docks) are awesome and I like hanging out there at night. Lots of the locals are there.
Also the Green Parrot is a good place to spend a couple hours and drink. There are lots of locals there, so it's a great place to meet very cool people. The bands are good there too.
We were there in June of last year, and our favorite place to eat was Salsa Loco (on Duval, near Truman St.). It's mexican and carribbean, with great flavor, good prices, and there's outdoor seating in the back. I think what we liked about it most was that there wasn't a band blaring in our ears, so we could sit at night in peace and quiet.
If you're a hot head, stop by Peppers of Key West, and try out some of their sauces (they will do progressively hot tastings, which doesn't sound as fun as it really is). Plan for beer or that frozen key lime pie on a stick afterwards.
Also, I didn't get to them the last time I was there, but it has been one of my favorite places to get a light breakfast/lunch: Cole's Peace. I think they've expanded considerably since being on the Food Network a couple of years back, but their baked goods were an awesome. (Think mushroom-feta foccacia, mango bread....).
One last thing- If you're driving, try to time it so that you can stop and see the sunset from the bridge at Bahia Honda State Park - it's a fabulous treat before arriving in Key West.
If you are driving down,Craig's ,on plantation key really does(as their sign says) have a really great fish sandwich,also as for that chocolate covered key lime pie on a stick, it is wonderful stuff, my favorite is the blond giraffe http://www.blondgiraffe.com/home.htm ,enjoy!.