2 weeks Spain & Portugal Itinerary

Buses and trains between Spain and Portugal are as reliable as any other transit option. It's just that there aren't many options. There is only 1 overnight train between Madrid and Lisbon. Book it early if you decide on that option. Buses probably have a few more runs and are probably cheaper, but will be even less comfy than the train. I'd compare prices and schedules of train, bus and plane and pick the one that best meets your needs.

Your railpass will work on Renfe but in most cases you will need a seat reservation. The overnight train of course is also an extra charge. I found for short trips (like Madrid to Toledo) it was cheaper to buy the ticket&reservation together rather than just the seat reservation using my pass. Strange but true. So if you plan on some short day trips, keep that in mind when buying your railpass. Always buy your tickets and/or reservations a few days in advance to avoid long lines and/or full trains.

Buses are cheap and reletively plentiful. But not nearly as fast and comfy as Renfe's high-speed trains. I would defintely take the train from Madrid to Barcelona; it's a pleasant 3 hour ride.

There are some great day trips from Lisbon and Madrid that are well covered in the guidebooks.

I'd also look into flying into Lisbon and out of Barcelona. It would be the most time efficient and might be cheaper when compared to the cost of going from Madrid to Lisbon and back.

I agree; fly into one country and out of the other. It will make your travel time much more efficient. I found buses to be easy to use and very reliable.

From Lisbon, I'd suggest visiting Evora for a day trip -- it's a great village/city with some interesting Roman ruins. I'd also suggest carving out at least a day or two to stop and catch your breath in Portugal's Algarve region, if at all possible.

In Madrid, I always suggest Pension Retiro, which is basically across the street from the Prado and maybe a block or two from the wonderful Retiro Park. But it's a budget hotel/hostal, so it's up to your personal traveling style. We loved it and found it quite convenient.

Have a great trip. I'm pretty much in love with the entire Iberian Peninsula -- both countries are just amazing!

We did a similar one last year. Arriving BCN and did the speed train to Madrid. We then took the overnight train from Madrid to Lisbon (departure was Lisbon). I preordered these tickets from RailEurope. We did day trips from each city. I can share my itineray to start you somewhere and assist in your plans. I sent you a personal message so you can email me if you wish to see it.

With the stops you already have planned, flying into Madrid and leaving from Barcelona will mean a LOT of back-tracking. Madrid is in the center of Spain....Lisbon to the west, and Barcelona to the east. Try flying into Lisbon and out of Barcelona (or vice-versa) or, at a minimum, flying into Barcelona and out of Madrid.
Flying is the best way to get between Madrid and Lisbon. Train and bus connections between Spain and Portugal are extremely poor. Try sites like whichbudget.com to see discount airline fares between the two cities.
You'll have to go to and from Oviedo via Madrid by train.....few cross connections are available.
A Eurail pass is probably overkill for this trip. Check www.renfe.es up to 62 days in advance, and you can book tickets on the fast AVE train between Madrid and Barcelona for up to 60% off....you print your tickets at home. The site is in Spanish, but it's do-able with a little help. Portugal's train system is a giant commuter rail system...the country's not that big, and tickets aren't expensive.
Frankly, with two weeks, your itinerary's already filled. Three days each in Barcelona, Madrid, and Lisbon, plus your trip to Oviedo, plus travel time, and you've already reached 14 days.