I recommend 3 full days in Seville.
In 3 days you can see the main attractions and have enough time to soak in the local culture. 2 days in Seville is also fine, but you may feel that it is a little rushed. If you have more than 3 days, use the time to see the region around Seville, there is a lot to see in Andalusia.
Seville in a day - Not Recommended
Of course, you can ride the high-speed train AVE from Madrid and visit Seville as a day trip. Do not be tempted to do this as you will spend 6 hours on the train.
Seville in two days - Visit only the highlights
A 2 day trip to Seville is very much possible but you will be cramming too much into too little time. To get most out of your 2 day Seville trip, you will need to heavily prioritize the sights you want to visit and activities you want to indulge in.
One advantage is that Seville is a compact city with most attractions close to one another. However, the heat and humidity will slow you down.
Seville in 3 days - Perfect Itinerary
Three full days is about the right duration of stay in Seville for an average tourist.
In 3 days you can see all the main attractions and have adequate time to soak up the culture and Moorish heritage of Seville. Tradition and culture is still a way of life in Seville.
Seville in 4 days -Include offbeat attractions
4 days gives you enough time to include some of the offbeat attractions that dot Seville and the region around Seville. If you are more of a conventional traveler, use the fourth day to go on a day trip to Cordoba or Ronda.
Seville in 5 days - Explore charming Andalucia towns
5 days will mean an immersive 3 days in Seville and an easy 2 days to see the rest of Andalusia around Seville.
Seville is the regional transport hub for Andalucia. From Seville, you can plan excursions to Ronda, Cadiz, Carmona, Osuna, Écija, or the White Villages (pueblos blancos) in the northern parts of Cadiz or Malaga province.
Tips for your days in Seville
However long you decide to stay in Seville, here are a few tips that will come in handy during your stay.
How much to Budget: Seville is not expensive and as a couple it should be very comfortable to budget as low as 150 euros a day.
Areas to Stay: There are some preferred areas but, really, you can decide to stay pretty much anywhere you like in Seville. It is a small city and everything that is worth seeing is a walk away. Even if the walks are long sometimes (rarely), it is fine because you are seeing a lot on the way.
Local Transport: Seville does have a good metro, tram and bus system… that you will in all likelihood never need to use.
City Tours: You will find no need to ride the city tour bus because Seville is a compact city; and many old parts are pedestrian access only, anyway. Take a walking tour instead.
Souvenir shopping: Your main buys from Seville should include flamenco and ceramics related items. Or Sherry. Avoid buying food until you exit Spain; this is just so that you don’t have to carry perishable stuff around the country from Seville.
Tickets for Main attractions: Booking tickets on the spot is easy at Seville attractions, including the major ones. Don’t expect long lines even during high season. If you are really keen to be safe then book only the Cathedral roof tour in advance.
Culture, Food and drink: You have to go on a taps tour of Seville. There are many options. And make sure you watch an authentic flamenco performance.
Recommended Seville itineraries
Here are some useful itineraries for you to refer to as you decide what you can do with your time.
1 day in Seville
Start with half a day in Santa Cruz. Visit the Cathedral; then visit the Real Alcazar. Walk towards Triana district via the Real Maestranza bullring by the river. Spend the afternoon roaming the Triana streets for ceramics. Visit the Inquisition museum. Have tapas by the river or come back to the historic centre for dinner.
2 days in Seville
You can spend an entire day in the historic old city. In addition to the Cathedral and Alcazar, you can also decide to climb the Giralda or go on the Cathedral roof tour. In the afternoon spend time at Plaza Espana and the Royal Tobacco Factory. On day 2, go to Seville convents to buy cookies. Spend the majority of the next day in Triana. You will also have time for a Flamenco performance. Here is a detailed two-day itinerary for Seville.
3 days in Seville
Add a day trip to one of the many Andalusian towns around Seville.
4 days in Seville
Go to Italica, which is very close to Seville. Come back in the afternoon and go to the Metropol Parasol structure. Climb the roof at sunset for a unique experience.
5 days in Seville
You can do all of the above but do it at a slower pace. Add in a walking tour on day 1 so you get to know the overview of the main sights before you get into them in detail. Find 2 hours for a session at one of the hammams.
Day Trips from Seville
If you have more than 2 days in Seville you must consider going on a day trip. Seville is very well connected to the rest of Andalusia and there are many places to choose from. Remember that a day trip from Seville to Granada is not a good idea; it is just too far.
Some places to consider are Cadiz, Jerez, Ronda, Cordoba, Andalusian white towns, Alicante, etc.