Yeah Sultanahmet is nicer, around 30mins away on train from Taksim Square. Couple of nice spots around the Hagia Sophia and Blue Mosque area and a few restaurants etc as you walk back down past the Basilica Cistern. If you go to the Hagia Sophia you can only visit the upper section as the downstairs is reserved for those visiting to prey at the mosque. Theres also loads of places to eat if you walk towards the Egyptian Bazaar from that area also