We will be traveling to Spain in early August and want to spend about a week on the beach. I'd love to hear any opinions on Costa Brava vs. Costa del Sol. Our interests are the beach, fun and nightlife.

Both Cost Brava and Costa del Sol have nice beaches but I myself prefere Costa Bravas since the water tends to be a little bit warmer there, due to that Costa del Sol has a flow of cold Atlantic water, and the beaches a little bit more varied.
The biggest differens between Costa Brava and Costa del Sol is that Costa del Sol is more exploited reg. tourism. You´ll find almost no free space from Malaga and half way down to Gibraltar making it a very intence area full of tourists and nightclubs.
When I´m there I´m usually around the Marbella area
which I find to be nice since you have all that Costa del Sol has to offer yet you´re not right in the middle of the touristey area. You can from there take great daytripps in the mountains or along the coast towards Gibraltar.
Costa Brava then has most of what Costa del Sol can offer. You´ll find that here everything is more genuine Spanish in the sence that tourist areas are spread more along the coast with Free space inbetween and it´s not as exploited. Here I´m usually around the Castellón de la Plana area but any place along the coast is as nice. You´ll find good nightlife but maybe not as intence as in middle of Costa del Sol. Here as in Costa del Sol you can take great daytripps to old villages and such.
Well hope you´ll have a great time.

I agree! The Costa Brava boasts some of the most beautiful unspoiled beaches on the Mediterranean versus the touristy Costa del Sol. I stay in San Pol a small town just south of the true beginning of the Costa Brava and it is breathtaking. If you do decide to go the Costa Brava, look into staying in Cadaques (spelling is undoubtedly incorrect here). It is considered by many to be the most beautiful village on the Costa Brava and I believe it is where Dali made his home and got his inspiration. Don't forget to spend a day or two in Barcelona -- the city is spectacular and is often called the Spanish Paris.

Have a wonderful trip!

Just about any coastal region in Spain during August will lively with plenty of nightlife with the exception of the cities as people decamp to the coast during Aug.
One area to consider is the Costa Blanca around Alicante, there is just about everything there, cosmopolitan nightlife in Benidorm but then areas like San Juan which are predominantly Spanish for a complete change.
The inland areas around here are fantastic also.
E-mail me if you want any further info.
Steve