Another easy-to-navigate-in-one-week trip that actually isn't bad in August: Barcelona.

Art and architecture galore. It'll be hot and humid, but you're on the sea so you can mix in a beach day in the middle to take advantage of that. Easy to get around on public transport. Cabs are plentiful if you want one, but you can make do on the metro without any difficulty. *No* need for a rental car. Your dollar goes reasonably far there (compared to much of Europe, anyway): our Renaissance hotel was just over 100 euro per night and there were lots of other options up or down the budget scale. There are certainly crowds, but almost every major tourist site in Barcelona has to be booked online ahead of time anyway, so that just means you have to plan. You don't need to queue at the sites themselves.

Mountains are nearby as well. Daytrips on commuter rail are easy and inexpensive. Montserrat is very much worthwhile...you could do some hiking up there too.