Spain in 7 days - first time
 

First trip to Europe. Thought planning was going to be easy, but the more i research the more i want to do; had tons of cities to visit planned out but had to begrudgingly narrow them down; am not set on them still. Take off July 17 return August 5. Itinerary is as follows:
* Land in London July 17 (friend is doing studying abroad there for law school and staying with him).
* Paris July 19-22.
* Take off to Spain the 22nd. Here is where it gets tricky. Plan do do Spain 22-29 as follows: Barcelona - Valencia - Madrid.
* Last week London.

Was wondering what you guys thought. Could i sneak in an extra city? Approximately how many days to spend in each city? Where would you recommend a good stay? Your time and help is deeply appreciated; am hoping to make this trip a good one. Thank you in advance...

7 days and 3 cities...I would suggest that you drop two not add more, well that is if you want to see something of Spain other than though a window of a train/bus/plane window that is.

UNless you have a friend or relative in Valencia, I would skip it this trip. Even your time in Paris is too little considering travel time.

Guys ,thank you kindly for your swift replies. Am narrowing it down to Paris (19-22) - Barca (23-24) - Madrid (25-29). Was considering dropping Barca entirely but hear its a must see when in Spain. Would you guys recommend I carry cash? Hear there might be places that don't accept cards in Spain. Thank you again for your help...

Carry cash? nope not good. CC not taken, like in all countries some places do some don't. Some may have a minimum limit of payment.
Use an ATM if you want cash.

Under your new plan, how much time will you actually spend in Barcelona? There is the perennial debate about which city should one visit Barcelona or Madrid. In essence, Madrid clearly has superior museums, while Barcelona is a more interesting city.

Always updated info on Madrid: http://www.esmadrid.com/en/portal.do

Fabulous museums, excellent food and the absolute best nightlife. Los Gatos (the cats) - as the madrileños are called - stay up at night.

The Veranos de la Villa (Summer in the city) festival will take place when you are in Madrid. Both national and international top artists on different scenes around town every night in July and August. The outdoor scene in the Sabatini gardens just outside the Royal Palace is quite spectacular. http://veranosdelavilla.esmadrid.com/index.php/