Spending a good amount of time on Las Ramblas and exploring the Gothic district is certainly on everyone's list of "things to do" when visiting Barcelona, it is just that Barcelona is so much more than these famous touist areas. If folks also want access to excellent shopping, restaurants, sights and the local Barcelona culture, I like the Hotel Claris. Just my opinion.
In Istanbul, I like the Hotel Marmar, which is nowhere near the Grand Bazaar, but visiting the Grand Bazaar is the number one thing to do in my opinion. However, dinner on top of the Hotel Marmar with a 360 degree view of all of Istanbul, superb service and excellent food is also something I would not miss. I guess it is all in what folks want to experience when they visit a port.