How easy is it to travel by train from Paris to Lisbon by train? What would you suggest?

It's a simple journey. Take an afternoon TGV from Paris to Irun (the first station in Spain) then the overnight 'Sud Express' which gets to Lisboa in the morning. The overnight train has sleepers and couchettes.
The "Portugal" page on www.seat61.com has more details.

I did this last year. I took an overnight from Paris to Hendaye. Then the local Eusko Tren to San Sebastian station Amara. A day walking about and eating tappas and drinking wine in San Sebastian!!! Then an overnight from station Norte (with luggage lockers) to Lisbon.

Just to warn you, its quite a long journey. I did the reverse last year, from Lisbon to Paris (via Hendaye) - we took an overnight train and the total time spent on the train was about 21 hours. Also, the train we took did not have any sleeper cabins so everyone had to sleep sitting up. The train from Lisbon to Hendaye (the overnight part) had 8 person compartments with 2 benches - we shared ours with 6 loud, drunk Portugese men so it wasn't the most enjoyable trip ever, but it was cheaper than flying!

Hi dk,

www.easyjet.com will fly you from CDG to LIS for as little as 35E + tax in under 2 hr.

There is only one overnight train between Lisboa and Irun/Hendaye and it does have sleepers and couchettes as well as ordinary seats. I certainly wouldn't want to do any overnight journey sitting in a seat, so you do need to book in advance to get suitable sleeping accommodation. The last time I used this train was in September when I booked the day before and the sleepers were full so I had to make do with a couchette.
One of the advantages of travelling by train is the opportunity to break the journey somewhere interesting. San Sebastian is a very good choice and the schedule allows you to have dinner there before boarding the train to Lisboa.

Sharing a bench with 6 loud, drunk Portugese men? Sounds like fun.