Please suggest a 12 day itinerary.

You will need to be more forthcoming with information. Such as when, how many of you, ages, budget, interests, etc., etc. All you have divulged is that you have 12 days for Spain.

Soniya, what we don't know about you:
What year/month you're taking your trip
What sort of budget you have
Approx. how old you are
Who is traveling with you and their ages
If any of you have mobility problems
What sorts of things you do and do not want to see/do
How you sightsee: independently versus guided tours
If you've every traveled abroad before
Etc, etc.

Spain is a big country so it's not really possible to create an itinerary for a stranger whose interests may be very different than our own. A great deal of making a travel plan requires doing a lot of our own reading so that the trip meets our preferences and not someone else's. I would suggest getting some good guidebooks and starting a list of things you'd like to do/places you'd like to see. 12 days is not all that long, and you don't want to spend more time in transit than sightseeing so it's always best to keep the number moves to fewer rather than more.

Forums are great for asking specific questions; they're not really a place for requesting complete itineraries based on no information at all. Take a browse through the RS Spain forum to see what sorts of questions other posters are asking?

EDITED
You have 13 nights all up in Spain.
Check tour companies right away to secure Alhambra tickets for June 11. Substitute Valencia for Granada if you can't get tickets.

Day 1 (June 3) Arrive Madrid - 4nts
Day 2-3 Madrid sights
Day 4 Day trip to Toledo
Day 5 Train to Seville - 3nts
Day 6 Seville sights
Day 7 Day trip to Córdoba
Day 8 Train to Granada - 2nts
Day 9 Alhambra
Day 10 Fly to Barcelona - 4nts
Day 11-13 Barcelona sights
Day 14 (June 16) Depart Barcelona

We are a couple around 50 years of age and are on a comfortable budget. I am interested in visiting madrid , Seville and barcelona among other places. Also please suggest some vegetarian resturants.

We are a couple around 50 years of age and are on a comfortable budget. I am interested in visiting madrid , Seville and barcelona among other places. Also please suggest some vegetarian resturants.

We are planning a trip from 3rd June to 16th June 2016.

Wow ..... that's only three weeks from now! Time to hustle! Good luck.

Yes. We leave delhi on the 3rd and reach Madrid in the evening. We depart from Barcelona on 16th morning. So we have 12 days excluding the travel days to plan. I am celebrating my 50th in this trip!

I had planned to spend
3 days in Madrid
1 day Toledo
2 days Seville
2 days Cardoba/Valencia
4 days in Barcelona.
Does this look feasible. Also should I buy the rail pass.
Thanks.

Congrats on your 50th. I celebrated mine 2 years ago with a trip to India. I hope you enjoy my favourite country, Spain, as much as I enjoyed your country, India.

3 days in Madrid
1 day Toledo
2 days Seville
2 days Cardoba/Valencia
4 days in Barcelona.
Does this look feasible.

Yes and no. You won't be able to get to/from Valencia easily. Drop it.

To avoid hotel changes, I'd go to Sevilla and stay there. You can then visit Cordoba as a day trip from Sevilla, or stop for the day (luggage storage at the bus station across the street from the train) on the way from Madrid or to Barcelona.

Try to spend a night in Toledo. You can put your luggage in a locker at the Madrid train station. There is only a commuter train to Toledo, so you must go round-trip from Madrid. You can do it as a day trip while staying it Madrid, but it is much better as an overnight. If you stay overnight (or even 2 nights, arriving in the evening and departing in the morning, so you have 1 full day).

How much time you spend in Madrid depends on what you want to see there. As a city, it pales in comparison to your others, but the art museums are among the very best in the world and the palace is beautiful. If you want to visit them, 2-3 days in Madrid. Otherwise, add time in Sevilla and/or Cordoba (it's a lovely place to stay overnight and spend 2 full days) and/or Barcelona (never enough time there).

Since you don't have much time to make hotel reservations, you may have to adjust the itinerary to what you can find at prices you can afford. Generally, Cordoba is cheaper than Sevilla (but that may be offset by the cost of day-tripping on the train - Sevilla definitely has more to see); Toledo is cheaper than Madrid (again compare after adding the additional train fares).

Read this article about Renfe trains in Spain. It has valuable information. Then use the Renfe website to plan your trips. You may still find some reduced fare tickets - read the restrictions, though. If your credit card doesn't work, you can pay with PayPal.

Thank you so much. I am reworking our plan. Any suggestions for which area to look for a hotel in Madrid. Any suggestions for tried and tested hotels in Madrid, Seville Cordoba and Bacelona. Thakyou once again!