From Paris to Toulouse

Yes, you can save both time and money if you book your flight early and can be a little flexible on the day of the week. Rail time will take about 6 hours and flying about 1 hour 20 minutes. Easyjet goes there out of Orly airport which is less of a hassle than flying out of CDG. Check their website for prices & schedules.

I'm pretty sure the TGV gets there in about 4 hours. You can check at www.sncf.fr. If so, the time to and from airports will be longer.

train is less complicated, especially if you factor in travel time to /from airports, as Doug mentioned above. once you arrive in Toulouse, you can take the metro from the train station and go into the city centre or take the bus or taxi.

The fastest TGV service takes just over five hours. If you book far enough in advance (up to 90 days allowed) at www.voyages-sncf.com, you can get Prem's fares as low as 25€. To get the best fare, book as soon as the 90-day window opens. The number of allotted seats is limited and they sell fast.

Once faced with a similar question, our solution was to fly into Toulouse and start our trip there.

That worked for us because it fit our itinerary (which eventually ended up in Paris) and of course it might not help you. But if you plan to head east, then north, as we did, it might be worth looking at.