Portugal in 13 days

We just returned from a great trip to Portugal that included a Douro River cruise.

I would skip the four nights in Coimbra. Yes, visit Cascais when going to Sintra.
Obidos and the Batilava Cathedral are must stops, but that is a one day trip.

Spend more time in Lisbon and Porto.

Consider going to Evora from Lisbon. From Porto, consider a day tour to Santiago de Compostela.

Your proposed itinerary will work, but I would recommend more time in the Lisbon area. With only four days, of which you plan on one day in Cascais and one in Sintra, you will not have time to see 1/10 of what you want. Lisbon and the surrounding area could easily keep you interested for all 12 days.

Although the port area in downtown Lisbon is getting touristy, you will find that most parts of the city are not at all touristy. This is a great city for wandering, and a good way to get started are the walking tours of Lisbon mentioned in Rick's guide.
Cascais is definitely worth a visit, particularly if you have local contacts there.
Public transportation in Portugal in general, and Lisbon in particular, is quite good. No need for a car unless you plan to visit rural areas. Cabs in Lisbon are inexpensive.
I recommend a google search for museums in Lisbon. There are dozens of interesting, small museums scattered throughout the Lisbon area. You could easily spend a week or two just visiting art museums in Lisbon. Note that there is a nice, small art museum in Cascais that out of town visitors rarely visit, the Fundacao Dom Luis I., up the hill from the Marina.
Rick's Lisbon guide and other guides will list some of the better known art museums, but there are many high quality small museums that are often overlooked.
I particularly like the Asian Museum near the Alcantara station (on the Lisbon-Cascais commuter train line).

In my opinion, 4 nights is 1 too many for Coimbra, unless you want to add a day trip to the really good Roman site at Condeixa Nova.

We left Portugal last Friday, 6/24. Do you have a Rick Steves Portugal guide book yet? If so, good. We used it lots while in Portugal for 16 days. If you want one it can be purchased elsewhere on this web site. I would recommend that you check out their weather shortly before your departure to assist in clothing options.

Hi Michele, I'd love to hear how your trip went - we are looking at a similar itinerary (reducing Coimbra per the advice). Also coming from Portland and looking for wine, wandering, art and adventure. Thanks!

Hi Leah and Michele - another Portlander here. Just returned from a too short visit to Portugal - Lisbon is amazing - I wish I had had at least two more days there. There are some great neighborhoods there and we only really hit 3 of them. Other highlights were Tomar, Milfontes (south along the coast) and the Alentejo area. Would love to go back and do more hiking and exploring in this region. And the wine from there is great.

Food is great - and the people are friendly and have a great sense of humor.