Hi Sue, welcome to the forum :)
I haven't done these trips with JY but I have been to Vienna and Barcelona independently. I thoroughly enjoyed Vienna; plenty of history, The Spanish Riding School, the ferris wheel from the Orson Wells film The Third Man, some good shopping etc. However I was rather disappointed with Barcelona. I know people rave over Barcelona but the only part I really enjoyed was a rather good pizza on Las Ramblas :-/
I personally would go on the Prague, Vienna, Budapest trip but that's just me.
If you really can't decide maybe it's time to trust lady luck with the spinning coin? ;)
Julian