Hoping some travellers might be able to throw around some itinerary ideas for 8-10 days travel through Portugal without a car (will rely on bus and train). I will be travelling alone and am a big foodie.
Feel free to post any ideas......
If Portugal is too much of a rush, was thinking the south of France for the same period. Any ideas???

Lisbon - Coimbra - Porto by train. Or just Lisbon - Porto with day trips. Fly into Lisbon and out of Porto or vice versa.

For train travel in Europe in general and Portugal in particular see https://www.seat61.com/

Yup what thursdayds says - Lisbon to Porto - do a day trip from Lisbon to nearby Sintra, for royal castles. Trains are good on that main line - no time for more than that. I enjoyed Porto as much as Lisbon but others do not. Yes for trains www.cp.pt - Portugeuse Railways; www.seat61.com - general train info and where to go by them - www.ricksteves.com and BETS-European Rail Experts.

I'd do 6 days in Lisbon - can do day trips to other places like Evora - and 4 nights in Porto- some nice day trips easy by train - research Guimares and Braga - about an hourby train and each really neat.

If looking for nice seaside old town between Lisbon and Porto check out Figuera de Foz! Coimbra too as thrusdayds says is worth a stop or an overnight =- especially to see its ancient university area and library area.

Any suggestions on where to stay in both Lisbon and Porto?

Budget? In USD or euro.