jkgourmet,
Unlike Ryanair services to "Barcelona", its flights to Valencia use the city's airport. It is easy/cheap/quick to get "downtown" from there by metro.
Reus, on the other hand, is near the interesting Roman town of Tarragona whilst Girona is a beautiful city in its own right.
Have you considered Madrid? Ryanair flies from Stansted to Barajas, which also has an excellent, quick (12 minutes from T1-2-3) and cheap (2 euro) metro link to the city centre. I prefer Madrid to Barcelona but others would disagree!
Enjoy your trip!