Let's start in the capital. "Tourists often overlook Madrid but there's a rugged authenticity here – quiet medieval lanes, glorious green spaces and tapas bars chocked with Madrilenos," says local travel writer and food tour operator James Blick.
"Dive into the neighbourhoods – Malasana, Chueca, Lavapies, Huertas," he adds, pointing out three must-see sights for first-timers: the Prado museum (audio guide recommended), el Rastro flea market and the "chilling" Valley of the Fallen Franco mausoleum outside the city.
But if you're hungry, dine off the beaten path. "In the Ibiza neighbourhood, there's a delicious enclave of swanky but affordable non-touristy tapas bars. It's traditional food with a modern bent – try La Castela, La Monteria and Taberna Laredo."
What about cities beyond the capital, though? "Head to northwest Spain for Oviedo and Santiago de Compostela – magical places with incredible seafood, steaks and wine," Blick says.
My own alternatives include San Sebastian for northbound foodies; Girona for that medieval Catalonian feel; Jerez de la Frontera for its Moorish fortress (and sherry scene); and Burgos and Santillana del Mar, with their picture-perfect old quarters.
Or how about the port city of Valencia, says local novelist and travel writer Jason Webster? "It's an undiscovered gem, a user-friendly version of Barcelona," he asserts. "There's rich history, fantastic food – this is paella's birthplace – and warm, welcoming locals with a passion for fireworks and fiestas."
Valencia virgins should start with the Central Market, the Gothic Silk Exchange and "the sci-fi fantasy buildings" of the City of Arts and Sciences. Then there's the grail. "Valencia Cathedral is home to the Holy Grail, authenticated by Pope John Paul II. It's in a special chapel near the main entrance."
Any other local hangouts? "The Cabanyal – the traditional fishermen's quarter – has many houses with colourful, century-old tiled façades. Rarely visited by tourists, it's home to Casa Montana, one of Valencia's best restaurants," Webster says.
Between Valencia and Cadiz, Andalusian capital Granada is another enticing old charmer, according to local expert Molly Sears-Piccavey. "There's 1,000 years of history here. And along with the Alhambra palace, it's great for discovering Spanish culture and gastronomy."
Additional must-sees include Granada Cathedral, the Royal Chapel and the Madraza; the Mirador de San Nicolas and wider Albaicin quarter; and the historic centre's many squares. Gourmands, she adds, should unfurl their appetites at the Mercado de San Agustin food market.
Any final tips? Aside from timing your visit for popular festivities such as the Crosses of May and June's Corpus Christi, plan ahead for Alhambra visits. "Book far in advance – tickets often sell out," Sears-Piccavey warns.
Travel writer Karen McCann says the south is a good region for intercity road trips, and suggests heading to Seville. "You'll find Spain's most vibrant street life here. Residents and visitors mingle easily in cafés where flamenco could break out at any time," she says.
"Seville's full of quirky charm and its spectacular Roman, Moorish and Renaissance architecture provides gorgeous backdrops for the festivals. The city isn't overrun with tourists – yet – and it remains welcoming and affordable."
After hitting McCann's must-sees – Gothic masterpiece Seville Cathedral; the Alcazar royal palace; and the contemporary sculpture Metropol Parasol – where can visitors detour from the tourist trail?
"The richly tiled Triana Market has fine produce, meat, fish and cheese from local farms and fishing boats," McCann says. "It's a feast for the senses with the aroma of espresso from tiny cafés and the cheerful bustle of families doing their shopping."
But what about suggestions beyond her hometown? "Historic Salamanca is humming with energy and has many offbeat attractions, including a cave where the Devil is said to have taught black magic. Don't miss the university's ancient library – it's like stepping into Hogwarts."
OUR READERS WRITE
Mallorca is a beautiful island of olive and lemon trees, jagged coastlines and sandy beaches. Tom Doyon
Seville for the amazing Cathedral and Granada for the magnificent Alhambra – plus great food, scenery, locals etc. @fraueibl
Valencia – it has fantastic white sand beaches and the most amazing aquarium, the Oceanografic. @Tamara_Elliott
Seville: spectacular food, beautiful art and some of the friendliest people I've ever met on my travels! @Gregory_Power
Valencia! A beautiful city full of culture and the incredible City of Arts and Sciences featuring the Oceanografic aquarium. @vanaqua
Loved the days we spent in Seville in September. I also bonded with Grenada – I could live there! @suefrause
Northwest Spain is grossly underappreciated. Salamanca is a lovely university town, with amazing architecture. Santiago de Compostela is equally wonderful, with vibrant nightlife (as long as you can tolerate the pilgrims). Cantabria region has some of the amazing paleolithic cave art sites (although generally closed to the public). And Basque Country is entirely unique in many ways – Bilbao is fantastic. Michael Ireton
San Sebastian and Laguardia or Logrono (in La Rioja). San Sebastian is a foodie paradise. Laguardia is atmospheric: there are medieval town walls and hundreds of cellars beneath the streets @KatieHammel
San Sebastian. The food choices (pintxos for a lifetime), the beach, the architecture – all combine to make this a great choice for city wanderers. Nearby Bilbao, Spain or Bordeaux, France, also add to the appeal of including San Sebastian on itinerary. @ngfalkeid
Ronda is gorgeous: steeped in history and built on high escarpments. I think it has Spain's oldest bullring. I took a short bus ride there from Malaga @JaneMundy
We flew into Malaga, rented a car and drove an hour to the mountain village of Frigiliana where we rented an apartment with views of the beautiful white painted village, hills and sea. Day trips were easy to the Alhambra and Granada as well as many of the Mediterranean coastal towns. One day we drove to Gibralter, then Tarifa where we spent a couple of nights at the Dar Cilla Guest-house with its incredible rooftop view of Africa and took a ferry to Tangier, Morocco for a day. On our last night in Spain we stayed in Malaga and experienced an authentic flamenco performance at the Kelipe Cultural Centre, that brought most of the audience to tears! Barbara Quigley
For us, Granada is a must-visit. And if you want to admire the sunset over the Alhambra, we invite you to visit us @RomanticGourmet
San Sebastian, Seville and Segovia. San Sebastian was a surprise: a beautiful beach area, stunning architecture and the best tapas bars @LorenChristie
Granada, Cordoba and Seville would be great cities to visit. Cordoba used to be one of the most important cities in the world, with one of the largest mosques that is now a cathedral. A unique mix of Christian and Islamic art, it also has the most beautiful houses in the in the world – and Andalusian horses @RShereenK
We enjoyed Ronda. With its Christian side and its Jewish/Moorish side separated by a bridge and the town situated on the edge of, and overlooking, a gorge, the views are remarkable. David Graham
Toledo! For the Alcazar, of course, and the El Greco Museum. Plus the food! @Lady_Astor
The city of Granada is wonderful. Plan on spending at least two days at the Alhambra – the gardens are magnificent and free! It's easy to spend another day or two strolling through the Albayzin. Take it easy like the Spanish do! The hop-on, hop-off bus tour is great for getting a feel for the city and where else you might want to spend more time. Rent a car to get outside the city. Finally, eat as much local ham as you can because you can't take it home. Joan Morrissey
I've visited many cities in Spain but my favourite is definitely San Sebastian (Donostia). Beautiful location, nice beaches and very good food! Close second: Granada. Gilles Bourgeois
Granada, Valencia and, of course, Madrid @CharlesMcCool
Granada: quaint, beautiful, amazing history and the Alhambra @k_kassam
"We've been daydreaming about a Hawaii trip after Christmas but our budget is tight. Any tips for a less-pricey Hawaii visit?"
Send your favourites to firstname.lastname@example.org
Follow me on Twitter: @johnleewriter