Which city is the best to visit? Cadiz, Malaga, or Tarifa?

Malaga is the only one I've seen and it's decent (Picasso Museum, "One-armed lady" church and the Alcazaba). Tarifa is small. But it you can live without the beach Sevilla is by far your best bet, and Cordoba second. You can't beat the sites in these two cities.

Malaga! I was there several years back, and it was beautiful and the people were so friendly!

The easiest place to visit from Granada would be Malaga. The unfinished cathedral, an ancient roman theatre, and the moorish alcazaba (a long self-paced tour is available) are all great historical things you could see. The shopping area is great and very sophisticated! Lots & lots of places to eat or have coffee. The beach is not that impressive. If a nice beach is the most important part of your trip I would recommend Cadiz. It will be a long drive from Granada, but worth the trip. Cadiz is considered to be the oldest city in western Europe. There are ancient roman ruins here also. The baroque style cathedral is nice, allowing you to hike up the tower for a great view. It is sunny almost every day of the year. The small plaza in front of the cathedral offers free wifi. There are two castles in Cadiz-Castillo de San Sebastian juts out into the water. Castillo de Santa Catalina is another castle located closer to the city center.

Tarifa is nice but very windy and quite a small town, if you visit there make sure you goto the old town part, but has to be between Cadiz and Malaga probably Cadiz as it's not as British although Malaga isn't as bad as some people make out

Your best bet then would definitely be Malaga. It has all things you want to offer: culture, history, architecture, beaches, shopping, nightlife (and an airport to boot). Also from Malaga you have all the sights within a few hours travel: Granada, Sevilla, Ronda, the Alpujarras, etc. pp. My suggestion would be to get a cheap rental car (straight from the airport, don't pay more than 120 EUR per week). Tarifa is just a very (very) good spot for windsurfers and kiters. Cadiz would be no. 2 in your list. It's not quite as big as Malaga, a bit rough round the edges and has a good few things to look at but not a lot more.

It has to be Cadiz, they don't fly the British flag in Cadiz because Sir Francis Drake razed the town on several occasions and the best beaches are a few miles out of town, the old town is spectacular though. There is not much at Tarifa (except a nice beach), Howabout trying a few spots such as El Palmar and Conil del Fronterra, or even Barbate, dont, forget to bring your surfboard because the area is inundated with decent waves at that time of year, beware to guard against petty crime though (theft from cars, pickpocketing etc.) Sevilla is tops but is the best part of 70 miles from Cadiz. (no beach though