8 days in Portugal
 

Dear forum members,

We (2) will be travelling in Portugal for 8 days this June, and I planned this itinerary after consulting some websites I have found, but I am completely unsure about it and open to changes. Would love to hear your opinions about it. Flight to Porto is booked, flight back is not.

I also add my planned budget, would like to hear your opinions about how realistic/exaggerated it is.

Itinerary
Day 0 (Monday) night: landing in Porto.
Day 1: Hanging around in Porto, tasting port, etc.
Day 2: Quiet morning in Porto, renting a car (plan to book it in advance), heading to the Douro Valley, sleeping in some camping site? B&B?
Day 3: Douro until bored, heading south, either via Serra da Estrela natural park (is it nice?), or straight to Aveiro.
Day 4: Hanging around in Aveiro + beach, heading to Sintra (2-3 hours drive), hanging around in Sintra, sleeping somewhere (B&B?).
Day 5: Road trip to Parque Natural do Sudoeste Alentejano e Costa, looks nice there, finding spot to rest, continuing to the south beaches (Praia do Amado, Praia do Beliche), perhaps sleeping in the middle?
Day 6: Continuing to Lagos, checking Camilo beach, in the evening heading back to Lisbon (almost 3 hours drive), returning the car, sleeping in Lisbon
Day 7: Full day in Lisbon.
Day 8: Almost full day in Lisbon.

Budget
Car rental: 300 EUR
Gas, Toll: 350 EUR
Lodging: 500 EUR
Food: 600 EUR
Extras: 100 EUR

Would appreciate any opinion regarding the itinerary and the accompanying budget. Thanks!