Regarding hotel in Barcelona, we've stayed at the Regencia Colon hotel which is next door, across the street, from the Hotel Colon. The Regencia Colon is a bit less expensive than the Hotel Colon. As noted earlier, it is a short walk to La Rambla and both hotels are maybe 4-5 blocks from Plaza Catalunya which is the major transportation hub for Barcelona. For example, there is an airport shuttle bus that drops off in Plaza Catalunya and the double decker tour buses use the Plaza as a starting point for a number of their tours. We used Bus Turistic, the Northern Route (Red Line), to visit a number of the Gaudi building.
Since I don't like the interference of street noise in European city center hotels, I always pack a pair of soft foam ear plugs to use when needed. Barcelona seems noisier to me perhaps because night life kicks off so late in the evening.
There is a fun restaurant a short walk from the hotels mentioned. It is called the 4 Cats (Els Quatre Gats). Here is the website for the restaurant (
http://www.grupferre.com/)
When we stopped off in Istanbul, we used the ship's shore excursion tour which was about 6 hours and really enjoyed the tour and the tour guide. The tour was spread over 2 days and cost was in the $125/person range.
Hope you enjoy your trip!
Dean