Take a hint, stay on the ship. Caracas is not worth a long drive and is dodgy when you get there and La Guaira is very dangerous and one to be avoided. Princess, P&O and OV use this port for cheap fuel, I wish they wouldn't because there other ports they could use with similar fuel prices but, if I know anything about it, higher port charges and they will do a lot to get a cheap berth. ... Neil.
Caracas is inland and about a 45 minute journey from the port of La Guaira where you will dock. It's many years since I was there but from what I remember La Guaira is very poor with many shacks illegally built right up the hillside (although there has been a landslide since I went so it may be different now). If there is a beach I doubt it would be very good or safe to use. As far as Caracas goes you may get some more replies from this site but, even when I visited, crime was rife and the tour guides were constantly warning us to watch out for pickpockets. I wouldn't recommend visiting on your own unless you speak good Spanish. Either way, dress down, don't wear flashy watches and jewelry and if you are using a camera keep it well hidden when not in use. It's certainly worth visiting but just be careful. This isn't a tourist resort, it's a very busy capital city. There are a lot of poor people there and tourists are a good way of improving their standard of living! I think simply visiting Caracas will provide more than enough entertainment for you. I'm sure you will have a great cruise.
Stay on board. Do not go ashore as before you leave the port you will probably be VIOLENTLY mugged like many others on the cruise I went on. Those people were warned but like so many they think they know best! well they do now!! sunbathe round the pool.