Trainline.eu questions - Munich to Paris

No reason I know not to use trainline. They are a European company. They used to be called Capitaine Train and were started by some people in France trying to improve on the less that user friendly SNCF site. They access the same tickets as the national railway company sites.

"Does the price I'm quoted on that site include both a ticket and a seat reservation?" - This is a cause of confusion. Tickets always include reservations if needed. Reservations are only ever separate if you have a pass.

"How likely (on any of the sites) am I to get the types of seat reservations I request (i.e. 4 seater booth, upstairs)?" - no reason you won't get what you ask for, if available. Your seat numbers are assigned when you buy the ticket.

"And last, is all upstairs seating an open saloon (my train is TGV 9576) or can an open saloon be specifically requested from any site other than DB?". AFAIK all TGV's are open seating only. I have never seen a TGV with compartments. Some DB ICE High Speed trains have a few compartments, but they are mostly open seating.
Not all TGV's are double deckers, many are single deckers. I have no idea which TGV 9576 is.

I have no idea which TGV 9576 is.

Chris, TGV 9576 is a direct TGV from Munich to Paris (6:23-12:10)

I meant I have no idea whether TGV 9576 is a single or a double decker.

Trainline is perfectly reliable and a great option. I'm using them more and more, they're just so convenient and easy to use.

Trainline is my preferred method of buying advance tickets for European trains. I've found them to be very reliable, and they have great customer service. Once you're registered on the site and have a credit card registered, the process is very easy.

Trainline is very good all prices the same as using the rail operator and all in English so no confusion unlike the Renfe site which is a mixture of Spanish and English

If you were booking a departure with a connection in Stuttgart or elsewhere within Germany, then the first leg would not automatically include a seat assignment, at least not in 2nd class. But one would be offered to you for 4.50 before checking out on the DB site. Since you've chosen the direct train which requires reservations (like most faster trains within France), then it is automatically included. Some shopping carts will let you select specific seats, which again you'll see before check out. Rail Europe doesn't offer specific seat selection. Your likelihood of getting any requested seat preference will always depend on how many other people have already booked on that departure. I also think all TGVs are arranged in open saloons, not closed compartments with 6 or 8 seats.

Thanks everyone. These answers are really helpful-I'll be booking with Trainline this evening!

It looks like in this case, for a trip between two countries, trainline has the best fare, but for trips inside Germany, for a number of reasons (accuracy, flexibility, options, information) I would still prefer to use the Bahn website (this link for English). At least use it for comparison.