It is not dangerous to visit the downtown Cancun, at the beginning of the strip. For families with kids, there is so much to do, they have small cars for $2 for 10 min for kids to ride in the park and many shops and restaurants. On weekend nights, they have good sales and the food there is good, at the stalls, I ate there even when I was pregnant and it was okay.
For the more adventurous, go downtown Cancun where the locals go. There are really two downtown Cancuns--the tourists' section, and the locals section. When we went in 2000, we were determined to see the locals section and did this by riding the bus at night to the end of Cancun. During the day, we found the locals market (Market 23). There the people had better prices, but some couldn't speak English. The tourists' market was fun too. The venders love to bargin and there is plenty of competition, so you can find some great buys. Hair braiding was really fast and cheap. Even the children will hustle you by coming from behind, slinding a woven braclet on your arm and saying "dollar." This became annoying though. Downtown is a nice break from the beach for at least one day.
They have different things going on throughout the week. I went to their GRAVITY performance that is shown earlier in the evening before the place becomes a nightclub. IT was an interesting experience. Dinner and then a show. Lots of audience participation. Pretty cool and worth checking out. Addmission runs about $65 USD per person.
This one is not as good as the one in Puerto Vallarta. It is two ships that sail together and in the midst of the voyage they join together for a dueling performance.
They have the dancing and contests. They have food which was just ok to me. My friend got food poisoning-allergic to pork. It does not land anywhere
The other passengers on board were more fun than the play that was put on. The service was decent though.
If you like iguanas just keep your eyes open while in Cancun, they are EVERYWHERE! Unfortunately, I have a phobia (YES I think its a phobia! LOL) of any kind of lizard and I cant stand them. Well they cant be avoided while in Cancun, I saw them on the side walks, beaches, everywhere! I'm sure they're harmless but ewwwwwwwwwwww! I took this picture while waiting for the bus and there they were just staring at me.
Take the bus into the heart of Cancun and explore down there. You'll find plenty of restaurants and maybe even a festival. The restaurants are good and cheap almost all around. Sometimes guitar players will wander in off the street and play personalized songs for you, but be ready to cough up some pesos for it.
Also, if you plan on sitting on the beach and just drinking a bunch, the supermarket is the best place to buy cheap Coronas or XX.
There are loads of these places around Cancun. This happens to be near the ADO bus station in Cancun. I just thought the name was a laugh. Although you can get two for one drinks.
Downtown shopping is the best. This is where you see the real beauty of the buildings. Just look at the only picture we have found of our CanCun experience.
Taxis to downtown are cheap.