Hi,
We too are doing a road trip --19 days-- in Portugal. We're starting in Lisbon for a day then renting a car to make a loop around the country, fly to a couple islands in the Azores and finish in Lisbon for another about day and a half.
Not sure if any of the following would be of interest but thought I'd post what we're doing.... maybe there's something along the way that you could use....
While we want to learn about the history of wherever we go, we are equally interested in learning about the natural areas of wherever we travel so with that in mind we include as many national parks, wetlands etc as well as try to visit any areas known for bird migrations or other animals. We also google ahead of time the best places to watch sunsets :)
If you have a map handy, here's where we're planning on visiting....Lisbon, Sintra, Obidos, Nazare (photos only), Tomar, Coimbra, Aveiro (photos only), Porto, Braga (only for gas up before entering park but possibly a nearby UNESCO site), Geres-Paneda Park (time only for 2 brief hikes to waterfalls), Vale do Coa (photos only), Monsanto, Evora, Parque Natural da Ria Formosa, Faro old town, Algarve, Pera Marsh, Lagoa dos Salados, boat tour of Benagil Caves, Setubal, Parque Natural da Arrabida, Tagus Estuary Nature Reserve, Sao Miguel Island (includes whale watching tour), Terceira Island (includes cave tour), Lisbon.
Portugal has 17 UNESCO world heritage sites and another 18 on a wait-list for approval, many of which are in the areas we plan to go through. And, we've learned we'll be in the area during the flamingo migration!
In reference to restaurants....We try to eat in local markets as it's less expensive than restaurants with the huge benefit in that it's local food rather than an adaptation of food for Americans. I'm also vegan so I use the app Happy Cow to find vegan and/or vegan friendly restaurants. Apart from that I'm sure there are many others on this site who can better assist with some fabulous food referrals.
All the very best in your planning! I can tell you right now that our only regret is not having at least 1 more day even 2, as we would have liked to have spent more time in the northern mountains to visit some of the villages and numerous waterfalls.
Happy planning! Have a wonderful visit!