Here is realistic.
If you don't have flights yet, fly open-jaw (Barcelona/Madrid). You waste time returning to Barcelona. 8 days is 7 nights is 6 full days. If you are arriving from the U.S. at least some of you will be zonked on Day 1, maybe on Day 2 as well. On Day 8, you are like to have a morning flight home, so you'll want to spend your last night in your departure city so you can get to the airport with ample time to go through all the procedures.
Every time you change locations you have to pack, herd everyone together, get to the train (with time for traffic on the way and finding your train at the station). Then you have to get from the train station to your hotel to check in and drop your stuff before you can go out to sightsee. If you travel in the morning, it's pretty easy to keep the group together and on time (unless you have a sleepy-head who can't get moving). But a morning train means 1/2 day of sightseeing lost. Taking a late afternoon or evening train has its own pitfalls - first, the herding thing. Then you have to go back to your hotel to get your bags. Then there's the whole thing of getting oriented to a new location - takes some time and more important, uses up your energy.
Realistically, you can see Madrid, Toledo and Barcelona. The others are too remote for a one-week visit. If you have to fly in/out of Barcelona, then I would stay in Barcelona, maybe a couple nights in a nearby smaller location. There's plenty to see and do in and around Barcelona to fill a week .