I think La Roca outside of Barcelona is the better of the two, but Las Rozas is cheap and easy to get to even without a car. The bus from Moncloa to Las Rozas stops in front of the outlet center. Since it's such an easy trip, you don't need to spend a whole day doing this. Half a day is sufficient.

With the exchange rate being not where I want it to be, these outlet centers have become a regular stop on my European city visits. Most are very inconveniently located, and you spend half a day getting lost before you actually get to shop. Either that or you pay for an overpriced tour van where they, not you, decide how long you're staying.

In comparison, the cheap and easy ride to Las Rozas is a gift.

While they're not giving anything away here, you can buy many quality Spanish brands for considerably less than retail price. You'll fine Loewe, Camper shoes, Tous, Custo Barcelona, Adolfo Dominguez and various Spanish shoe companies.

They also have outlet stores from many other European brands such as Versace, Bally, Barbour and Burberry.

Also, at outlet centers, the salespeople are not as paranoid about customers handling the merchandise as they tend to be at downtown designer boutiques, so shopping is much more relaxing.

You can get information from their website: http://www.lasrozasvillage.com/es_ES/

It seems that they have opened many new stores since I was last there.

The outlet center at Las Rozas is located across the street from a kind of amusement park with a lot of restaurants, so you don't have to eat at the one place the outlet center offers.