In the Keys, we refer to distances in Mile Markers (eg: mm 80, mm 10, etc). When you enter onto Key Largo (the first Key off the mainland) you are at approximately mm 107. Key West would be mm 0. B/S means Bayside, O/S means Oceanside of US 1.
Key Largo is about 60 miles from the MIA. When you rent your car if they tell you to take US 1 down to the Keys, do not listen to them. You'll want to get of the FL Turnpike and take it to the end (which is Homestead/Florida City, the last city on the mainland. The turpike then ends onto US 1 where you will travel about 18 miles to Key Largo Key.
This portion of US 1 is under contruction with widening and a new bridge at Jewfish Creek but you are traveling at the height of slow season, so I doubt you'll have any problems. There is an alternate route to Key Largo via Card Sound Road that you can pick up in FL City (ten miles longer with a one dollar toll). Just look at a map to find it. It'll dump you onto US1 at mm 107.
Places to stay:
Like I said, you are coming at the height of slow season. You don't need to make reservations, hotels will be crying for business. In Florida City you can stop at any gas station or burger king and pick up a free travel magazine with tons of hotel discounts from key largo to key west.
Things to do:
Keep in mind, the Keys are built on ancient coral reefs. Two inches into to soil and you hit solid limestone. Therefore, beaches like you may be used to up on the mainland don't really exist. What little do exist are usually on private land. So most of the hotels have man made beaches on property. The exeptions are Long Key State Park (mm 60) and Bahia Honda State Park (mm 18?) Bahia Honda has one of the top rated beaches in Florida. Key West has a big beach on the eastern side of the island called Smathers Beach. Smaters is free but you'll have to pay to get into the State Parks.
Diving or Snorkeling:
The reef stretches from Key Largo to the Dry Tortugas but the best diving and snorkeling is up in Key Largo. Key Largo is the dive capital of the world. The reef is about four miles off shore so don't expect to be able to jump into the water from your hotel and see anything. You have to take a charter boat to snorkel or dive the reefs. For diving, there is the Spiegel Grove, a 510 ft navy ship sunk off shore. Other ships are the Duane and the Bibb, or you dive the reefs. Mollassas, the Elbow, Grecian Rocks are all good places. If you go Diving, try Quiessences (mm103) or Ocean Divers (mm 99.5) If you are going to snorkel, go with Keys Diver accross from the Holiday Inn at mm 100. Take the 12 noon to 4:45pm trip. It costs $6 more than the three hour tip and is well worth it. They'll take you to three different spots. They are the best in the Upper Keys.
No trip to the Keys will be worth shit if you don't eat at the Fish House (mm 102 O/S) One of the few restaurants that still use their own fisherman. Fresh Dolphin, Grouper and Yellowtail snapper (only found in reefs south of miami and in the carribean) If you can eat some Hogfish, do it. Rare, but the best fish out there. Fish House has fresh florida lobster too. A bit pricey, but everything in the Keys are expensive. The fish house closes the month of Sept. but they have a sister restaurant next door that'll be open.
Fishing:
if you want to go fishing, and don't want to charter a boat ($500 to $750) you can go out on the "Party" or "Drift" boats (45ft boats that take 15 to 20 people) for about $25. Since it's slow season there won't be a lot of people and you'll have a great time. You can find these boats all up and down the Keys. Just ask. Note: Islamorada (mm 80) is called the fishing capital of the world.
Night Life:
Key Largo sucks and slow season makes it even worse. You have the Caribbean Club at mm 104, Coconuts mm 100 (Ladies night wednesday) and the Big Fish Grill (mm 98.5) that's about it.
Islamorda is a little better. Holiday Isle resort (mm 84) is a great party place and if there is a full moon there is a huge party a Morada Bay (mm 81). Woodys is a strip bar (mm 80) but you won't find any sistahs.
Not much in Marathon (mm 50) so if you want nightlife, you best head for Key West.
As you can see, depending on what activity you want to do should dictate which Keys you want to visit.
Oh, yeah, one more thing. Don't Speed!!! US 1 is patrolled heavily by the Florida Highway Patrol and there are a ton of speed traps. Not to mention the Keys have more county sheriffs than the entire fuckin mainland. Other than that, you should have a great time.
