I am planning a trip to europe in June with my boyfriend and two kids (14 and 12). Rountrip to London, then taking the chunnel to paris for the first 3 nights, then eurail(?)from Paris to Barcelona for 3 nights and back to london. Any suggestions or tips on making this trip go smoothly?

When I tried booking an overnight train from Paris to Barcelona last year, they were all booked (on a Saturday night). Instead, I booked an overnight train from Paris to Port Bou (very close to Barcelona) and then took a regional train in. Just something to keep in mind if you run into the same problem.

Easyjet has very cheap flights. At night you can take the hotel train.

You wouldn't want a Eurailpass but if going round trip and not doing the oft frustrating PREM fares online the France-spain pass would probably be a great deal for you - it also gives you a passholder fare on the London-Paris Eurostar of $75 - available if available on any train any day - especially great on weekends and Fridays when $150 fares are the more realistically cheaper norms. And pass holder fares can be booked easier than the discounted $150 fare! For info on the pass i always recommend BETS (800-441-2387) for their expertise in my years of dealing with them and lack of mailing fees. They can also book the hotel train that goes direct Paris-Barcelona - again passholder fares available on this fancy train. The hotel train is one of the very few trains that go direct between France and Spain without changing at the border due to tracks in Spain being wider than those in France - the overnight Talgo hotel train has wheels that can move apart more to accommodate the wider Spanish rails - otherwise you could take a cheaper overnight train to Port Bou, on the Spanish border and change to a regional train that goes onto Barcelona, arriving about noon as opposed to 8:30am on the hotel train. On a railpass an overnight train in one day of a flexipass - the next day is your unlimited travel day if you board the overnight train after 7pm - the hotel train leaves Paris about 8:30pm.

I've taken the Trenhotel from Paris-Auterlitz to Barcelona several times

Tourist class offers a four-bed "roomette" which might be ideal for you.

You can check the options at www.elipsos.com

Compare the costs (you'll get a price break if traveling on a railpass) to the possibility of an EasyJet flight Paris-Orly to Barcelona and also Barcelona-London Gatwick
www.easyjet.com/en

I just went from Paris to Barcelona last month. We found easyjet to be faster, cheaper and far easier than any other option. Is there a reason you are considering a train instead of flying?