ADO is cheap and relatively easy, but for four people with luggage, you might consider some private or semi-private transportation. SupperShuttle usually has decent prices.
You didn't mention which airline you're flying. For the majors like American, Delta, and United, you'll fly into Terminal 3. It's pretty hard to get lost there. For the secondary/cheap airlines like Frontier, Southwest, and Spirit, you'll come into Terminal 4. They do stupid things in T4, like paint the doors so it looks like you're walking into a dead end, almost forcing you to stop and ask the touts for directions. But the key piece is the last left turn to commercial transportation, versus going straight out to friends and families. They now have a guard at that point to herd the tourists in the right direction, but if you miss that turn, you're out with the REALLY aggressive touts.