Lisbon-Sevilla transportation

The rail systems do not interface well. My assumptions without checking schedule would be a combo of bus and rail. What have you looked at? Bus is pretty cheap in Spain.

Kit - define "best"? Personally, I think the best way would be on a chartered private jet - with someone else paying for it. Of course, that may not be an option. As you have apparently discovered, the rail connections between most of Spain and Portugal are not very good. The answer to your question depends on multiple factors - how you're traveling around at either end (trains? car? bus?), how budget conscious you are, how much of a hurry you are in, your tastes, and other factors (even what day you're going). If all you care about is getting between the two cities at minimal cost, then bus (or as Frank says, maybe bus + rail) could be best. But there are other ways (fly, drive, etc.).

Thanks! Yes, I am in a time constraint, and have looked at rental cars ($300+/day as we need it in Spain as well), train/bus, bus only, and air (must go thru Madrid). So, I am a bit stymied. I did see a post somewhere that there is a train link-up, and I will explore that next. Any help is appreciated.

Hi. Kit again... Has anyone used the ALSA site to book a bus trip between Lisbon and Sevilla? They have an overnight bus, leaving Lisbon at 10:45pm, ar. Sevilla 5:15am.
Just wondering if this is my best alternative. Thanks.

Some additional things to consider... You say flights must go through Madrid and are all expensive. Are you sure? I believe there may be direct flights between Seville and Lisbon, but they don't go every day, just a few days a week. Try a more flexible search and see if you have any better luck (assuming you have the flexibility to adjust the day one way or another). FWIW, I just looked at some random dares in June (you don't mention what part of the year you're going - some of these flights may be seasonal) and found direct flights between SVQ and LIS for only $140 round trip - that probably doesn't include all fees, but still - there do seem to be direct flights, and at least some of them look pretty inexpensive to me. Check Iberia, TAP and Spanair - those are the three airlines that come up with my first quick search. You also mention that you considered a car, but it worked out as too expensive and you need it in both countries. Car rental shouldn't be terribly expensive, but the typical gotcha there is a ginormous drop off fee if you rent in Spain and drop off in Portugal (or vice versa). But there are a couple ways to beat that. First, can you arrange the trip so you pick up the car in one country, drive it into the other, then drop if off back in the country you rented it from (not necessarily the same city, just the same country)? You might need to get creative with your routing, but it's worth considering. Or, rent one car in Spain and use it there, drive to some town close to the border, drop the car, take a bus or taxi or train across the border into the other country, and pick up another car there, and drive on. This obviously requires some coordination and extra hassles, but it can be done - and it can save hundreds of Euros (I did it for that reason). Hope some of that helps.

Did you check Tap Air Portugal? We flew them in 2009. I just pulled up a random date in February and it shows a flight at 18:00, landing at 20:00. It looks like there's a one hour time difference, so I'd guess they're still flying direct. It's about the best way to go if they've got a flight on your date.