After you’ve hit Madrid and Barcelona, then Granada is arguably the best choice to take a deeper dive into what Spain offers. This city is the capital of the Andalusia region so it has a distinct history and even more interesting architecture.
The main attraction here is the huge Alhambra palace complex combined with the Generalife gardens. Visiting them isn’t exactly cheap, but once you get there you’ll see why and you’ll agree that it’s very worthwhile.
Food and drinks in Granada have prices similar to what you’ll find in the larger cities, and the usual advice of looking for bargains at places without English-language menus out front applies. Two days should be enough to cover the main sights here, though it’s pleasant enough that you might be tempted to stay longer.