~15 Days in Spain - Is this itinerary TOO much?

You do not say what time of year, which can make a big difference (summers: it'll be awfully hot in the south).

I recommend you do NOT do a "day trip" to Toledo. Because that's when every packaged tour group in the world does. And they all see Toledo at it's worst -- very crowded. Instead, spend the night there, and enjoy the magical old city when it's essentially free of day-trippers.

Get tickets in advance for the Alhambra to avoid disappointment (it's one of Europe's most popular tourist attractions).

If you are going to spend a half-day in Cordoba, rather than going out-and-back to/from Seville, do Cordoba as a half-day stop on the way from Seville to Madrid. The high-speed train from Seville to Madrid goes right through Cordoba, so you will pass through it on your way anyway.

I'm not sure I'd burn 1-2 days for the beach experience at Nerja. IMHO there are better things to spend your time on in Europe, so I would enjoy a great day at a beach closer to home, and spend that time in one or two of the amazing cities that you are blowing through a bit too quickly.

I agree with David except for one thing, it’s best to spend the night in Toledo. After one visit in Toledo in 2008, I too thought it would be best to sleep there one night and did when I returned in Mar of 2012. When the tourists left the city shut down. As I walked the dark windy streets of the old town nothing was open nor were there people out walking around. I went back to my room where I felt more comfortable. Maybe it’s changed since but it is more convenient as a day trip.

Your itinerary looks good to me with the exception of Nerja which I would remove.
Alhambra is correct spelling in Granada. Book tickets way ahead.
Ronda- might want to visit after Granada?

You won’t want to do that itinerary during the summer when temperatures in Granada and Seville are more than 100 degrees.

To be plain—yes. Yes, it is too much.

You have just one full day in Barcelona, in addition to your arrival day. (Gaudi is A main attraction, but the city is SO much more than just his architecture, which won't fit into one day, anyway.)

Another scant day and a half in Madrid, the capital city. You could spend the whole two weeks in the city and its surrounds and not only see sights and monuments, but also catch the vibe of the second-most populous city in the EU.

I could go on...

Spain has lots of historical sights to see, but if you don't mix in a whole lot of time for languid coffees/beers/fantas/vermuts in plazas or on terrazas you're doing the contemporary country (and yourself!) a disservice.

I agree about Toledo. You don't want to do a day trip; it'll be mobbed. Maybe reverse your plans for days 14 and 15 and spend the night in Toledo? (I also agree with the caution about the weather. The south, obviously, gets really hot, but Madrid, Toledo, etc., also get really warm in the summer).

I'm in the minority about Ronda--I found it underwhelming (gorge view aside) and a bit dull. I think you can easily see it in a half-day trip, and could use the extra time to build some more flexibility into your Cordoba-Seville plans.

Caroline

Hi thank you for the responses! I will be going the very last week of August to the first week and a half in September.
Instead of a beach day in Nerja would you recommend I stay another night in Barcelona or is there something else I should see or go do?

Forthrightly your itinerary will accomplish a lot of "see", but little of "Be there". Have you examined a map to understand the vast amount of geography you will be covering. Please do not underestimate the impact of high heat on your body during this time of year. Heat + crowds = Bake your meat!
Granada is great, but we prefer Cordoba.
Recommend: Barcelona, fly to Seville then train to Madrid.
Day 2 to 6 Barcelona. Spend a half day at beach, also day trip of your choice as Barcelona metro system is super easy connection to rail system.
Day 7 to 11 Seville. You can day trip to Ronda. Also spend a half day in Cordoba as a train stop on your way to Madrid.
Day 12 to 16 Madrid. Highly recommend an overnight in Toledo.

Proposed changes minimizes travel stress and expense, optimizes more time to "Be there" and still provides a massive menu to provide opportunities to create wonderful travel memories.

I have a better idea, although it's not what the OP is going to want to hear...drop Barcelona from this trip.

Of course Barcelona is great, and well worth a visit (it's also worth more than a day or two...). But it's an outlier, geographically speaking (also culturally). The OP's trip is on the short side, if they are going to stretch it to cover all the places on their list. Stop thinking of Barcelona as part of Spain (the locals will like that, by the way...). Barcelona can be included just as easily in a later trip to southern France -- it works as well on a trip to southern France as it does on a trip to Andalusia. Spain is a large, diverse country (kinda like the USA), a fact I think most Americans fail to grasp. You can't see all of it in one 2-week trip, no more than you can see all of the USA. Cut Barcelona (and the lost travel time it takes to get from there to "the rest of your trip") and you regain a couple badly needed days.

Skip Barcelona, and skip Nerja, too (it's not nearly special enough to justify burning 2 days). That gets you back 4 or 5 more days that would allow you to slow down a bit and make the pace less brutal (especially in the intense summer heat). I know this is a hard pill to swallow, but it would make your trip to Spain better and more enjoyable. Consider saving Barcelona for a return visit (there's more of Spain to see and enjoy, you will want to return).

I must write a few words of support for David (the comment just above this one at the moment), for I've found it unusual to see this sort of good sense on forums like this. I'm referring to his general point, on the hopelessness of "seeing everything" in a large, diverse country like Spain in a trip of around two weeks. As for that most common forum question -- "is one day enough?" -- I guess I would say that if all you want to to is check it off a list and say you've glimpsed the place, or instsgram yourself standing in front of whatever Famous Tourist Spectacle it offers, one day would be enough for a great majority of the world's cities and towns.
This doesn't necessarily mean that you should skip Barcelona; I'm sure it's a great city to see. What I will say is that I've made five great trips to Spain myself, without so far seeing Barcelona. But I'm sure I'll get there one of these days.

Alternatively, if you really want a beach day (and, in August, I can definitely see the appeal) and want to keep Barcelona (the above posts suggesting cutting it make a good point), there are plenty of options along the Costa Brava (and you could see towns like Girona and Besalu as well). That's just a suggestion. As I said, I agree with some of the other posts that narrowing your geographic focus might be a good idea.

Also, I love southern Spain, but late August is going to be brutal. Unless you really, really, really have to go to those cities (which I certainly can sympathize with), perhaps reorient your trip north? You could fly into Madrid and out of Barcelona, or vice versa, and see a good bit but in a less hectic fashion.

Lastly, given the time of year, if you're still open to location suggestions, you might consider the northern part of the country. I think "Green Spain" is a very special and underrated (by North Americans) part of the country and well worth a visit.

Caroline