We are a family of five with three boys (ages 15,14,10) and booked inexpensive rountrip flights to/from Madrid June 19 through July 12. In total, we'll have 23-Days and would like to mainly visit Spain but add in some Portugal as I have a friend near Lisbon. I would like suggestions and/or thoughts on how to make this as seamless as possible and any suggestions to consider. Seems like inexpensive flights are abundant and can get to most places via the air for less than $70ea which is fine for us. We're okay with trains, but not necessarily long buses. I have experience renting cars and driving all over Europe - so can consider that as needed. Here are my initial thoughts:

Day 1: Arrive Madrid and immediately fly out to Lisbon.
Day 1-7: Portugal. Should we split up Lisbon and Porto? or stay in one place? How many nights is ideal? Are 6-nights too many?
Day 8-14: Barcelona. This too many/few nights?
Day 15-21: San Sebastian or Malaga/Marbella. Debating going north or south--not sure which would be more interesting for the kids. Too many nights?
Day 22-24: Madrid. See some sights, maybe Toledo day trip. Return home.

We can arrange in any direction and spend as many days as makes sense. Don't want to be bored and spend too many days in one place, but don't want to be nomadic either. On the fence between the south of Spain vs the north (Malaga/Marbella vs San Sebastian). Thanks for any insight guidance provided.

Looks like a pretty good plan.
Andalucia and Basque country are fairly different. Should be easy to determine which your family would enjoy more. I like Malaga, but it would not be my first choice (Sevilla probably). One will be warmer?

Your places are far apart so flying would be best except maybe S Sebastian to Madrid. Consider doing Lisbon-Porto- night train to San Sebastian or fly - train to Barcelona and train to Madrid - be sure to do a day trip to Toledo. For lots on trains check www.renfe.com; www.seat61.com; BETS-European Rail Experts.

Climatewise the North will be cooler, Andalucia can already be hot - but I assume from your nickname that you should be quite used to heat.

I'd probably be leaning towards Andalucia - a rental car could be of use for going from Sevilla to Granada (Alhambra!) and Malaga (beaches!).
Marbella has a nice old town, but not sure if that was too exciting for more than 2 hours.

The North is quite different - between the coastal regions on the Bay of Biscayne and Barcelona you have the Picos de Europa and the Pyrenees.
So even high mountain hiking is perfectly possible in Spain.
The longest and best beaches are west of Gibraltar on the Costa de la Luz, closer to Sevilla. But at the beginning of the summer season those Atlantic shores can still be a bit more chilly (as the Algarve), so when swimming is on your list, the Costa de la Sol or the beaches in or nearby Barcelona promise higher water temperatures.

Lisbon is a box of wonders, lots to see and do in the city. Also many options for easy day trips by train to, for example, Sintra.
Not sure if I wanted to do both Lisbon and Porto in one trip if I also wanted to see more/different regions of the Iberian peninsula.

Yes consider doing Lisbon then taking a train to Algarve - Tavira I found was a neat town - then bus to Seville and spend time in Andalusia and go to a beach area like Malaga - fly to say San Sebastian - train Barcelona and Madrid.

As cowboy says above lots of places in Andalusia - Seville, Cordoba, Granada and Malaga all gems and easy to take trains and buses between them.

Renting a car in Portugal and returning it in Spain may involve prodigious drop-off charges for doing so. But a driving trip Lisbon-Andalusia- coast to Valencia and Barcelona and end in Madrid could be sweet but that's a lot of long driving days.

Should be nice! But note that your counting is actually off, as it doesn’t include your travel time. So, for example, you don’t really have day 1 in Portugal – that day is a travel / get oriented day. I see that you said your time is flexible, but wanted to alert you to this problem. It’s generally much more helpful to lay itineraries out by nights, rather than days.

I wouldn’t think a week (even if you had that much time) in Barcelona too much, particularly because you have a wide range of easy day-trip options – Montserrat, Tarragona, Girona, and more!

As yorkshire said, Andalusia (Malaga) and Basque country (San Sebastian) are so different that I don’t know how we could comment without knowing MUCH more about your interests, while your family should be able to make a choice rather easily. And whether a week is right or not depends not only on what you want to see and experience, but how far afield you are willing to go for day trips. If you really want to see Basque country, a week could be about right; if you want to see more of the northern part of Spain, a week is probably far too little. If you really want to see Andalusia, a week is too little. If you want to see little bits of places, your timing could be just right. I would urge you to do more research, perhaps using guidebooks (I'm a great fan of them!) and perhaps to include reading trip reports and especially planning threads here on Fodor's.

By way of contrast, just a few days in Madrid is, IMO, very, very litte. I’m glad I had 2 full days just for Toledo!

Hope that helps!

OP Some observations for you.
When planning a trip the amount of time is counted in nights, not days. You have got both.
We do not know what dollars you are writing about as there are many of them. Perhaps it would be better for all to use Euros as that is the currency for this trip.
You have stated you have found flights at bargain prices. However you have not said which airline these flights are with. Just hope it is not Ryanair or Iberia.
Appreciate your friend is in Portugal, but either you make that the area for this trip or drop it from your itinerary. You can always do it another year and it really is at odds with destinations in Spain.
If you rent a car. You will need a childs seat for the youngest plus none of them can sit in the front seat.There is a requirement that each driver has an IDP.

The question(s) about how many nights and what to see are relative. Unfortunately you have divulged what you and your children's interests are.
Finally you say you don't wish to be nomadic, but your ideas of where to go certainly cover some kilometres. I would suggest you slow down and see more.

Also need to have spare pair of spectacles in car if you need glasses to drive marked on your license.

I too thought of saying to ditch Portugal and instead start in Madrid -drive to Basque Country and S Sebastian - Pamplona - Barcelona - Valencia and back to Madrid or take trains on all of those easily.

Andalusia as said can be very hot in early summer even. From S Sebastian could easily dip into France for a few days.

Or if Andalusia - spend days in Madrid then train to Seville and rent car or take trains and buses around - train to Barcelona in about 6 hours or fly - train back to Madrid

If doing Lisbon then do Andalusia too and then Barcelona - Madrid.

Law is never enforced just like carrying around spare bulbs for the car's lighting system.

I went to Madrid and Andalusia in October and really enjoyed Andalusia, but for the time of year you are travelling, I think I might opt for the north. It gets really hot in southern Spain.

Thanks to everyone that has suggested key points to consider! I'm going to dig deeper into the guidebooks and online research and will see if anything stands out as a better fit for my family. We are flying United from Phoenix, Arizona to Madrid both ways. We have traveled throughout Europe a couple times as a family, and the kids love to eat everything--so food and culture is a top priority for us. Based on past experiences, in warmer climates, we like to only schedule one main activity for the day (about a few hours) and leave the rest of the day open to stumble on things or to relax. In the summer in London, it was go-go-go for hours upon hours, whereas in Rome it was one main sightseeing excursion then a siesta because the heat wore us out.

Portugal has always been on my list and I just feel like having these many nights we can finally do it. I know it will impact part of two days with travel, but it's something that I really want to do if possible--even if it's just for 5 nights. Trying to find a place for 5 people always factors into the equation and sometimes steers us to one place over another. We prefer hotels, but have had some success with rental properties as well. B&B's are the best if we could find great ones as we love having those breakfasts--but it's hard to find an upscale B&B (any suggestions on that for any of these cities)?

Have you tried searching for B&Bs through booking.com?

Been researching and thinking about this a lot, and I think we're going to just focus on Madrid and Andalucia. My wife and I have already been to Barcelona and as many of you pointed out we'd be covering so much and hurrying more than I'd prefer. I hope it's acceptable if I post a new thread asking for 14-nights suggested itinerary starting in Madrid and focusing just on Spain. I think my title has too many variables (24-days plus Portugal). If you can take a look that would be great. Thanks!

Absolutely acceptable and in these circumstances (and for the reasons you mention), preferred.