ready to book train - can you tell me where to buy and if the below works?

Start with Voyage-SNCF, which is the railway, and will offer the best seat selection, including facing forward for this route. If it won't take your payment (try PayPal if offered), then go to either Rail Europe (in US$, no detailed seat selection) or Trainline.eu (in euros). Any of these should have similar rates. I don't believe this is a "duplex" type of train.

You could buy your tickets when feet on the ground in Switzerland. SBB only sells on-line tickets a month ahead.

The ICs have open seating other than first vs second class cars. https://www.seat61.com/Swiss-trains.htm#What are Swiss trains like

Swiss trains run substantially on-time where a 5 minute connect is not a concern.

Monday September 18 Lucerne IR 2316 leaving 10:54 to 11:55 to Basel to catch the TGV 9218 at 12:34-3:37 giving us 39 mins connection in Basel (enough?) arriving Paris Gare De Lyon which site is best to book these trains TGV Lyrica

Have you already got your ticket from Basel to Paris? If not, do this as one booking from Luzern to Paris. You don't have to do different bookings for each train, do it as one booking on the Swiss Railways website: https://www.sbb.ch/en/
They are currently offering the trains you list for CHF 66, per person 2nd class.

39 minutes to change trains is an eternity. As Edgar says, 5 minutes should suffice.

If you have already got a ticket for Basel to Paris, just buy a ticket from Luzern to Basel on the day. For Swiss internal trains there is no discount for advance purchase.

On the Swiss train you have free choice of seats. On the TGV, I don't know how to tell what your seat will be. Some TGV's from Basel to Paris are single deck, some are double deck, I don't know which is which.

For Eurostar, use the Eurostar website: http://www.eurostar.com/uk-en

Thanks everyone! I was going to do it as one booking and the reason I wanted to book ahead was to get the best fare on the TGV. I had read this post https://www.tripadvisor.com/ShowTopic-g1-i12483-k10189984-Do_NOT_use_www_trainline_eu-Train_Travel.html I don't even use expedia in US - I may search it for prices but I always call the hotel, car, etc directly. Some had said if you use raileurope to change your location - don't chose US etc. I'll look at what y'all suggested and also for Eurostar I will book directly with them. The time I found for Eurostar works for my schedule and is cheaper than others on that day so I was going to go ahead and grab that unless yall tell me not to

Re-read what ChrisF said about booking on SBB.ch as that is the best option.

As far as choosing a seat on the TGV, try the Man in Seat 61 website for more information on the trains---sometimes he has seat maps of the specific train, showing the direction of travel so you can choose a foreword-facing seat.

thanks i am going to try right now . I had been told that they only did one month out but i'm gonna try all suggestions.

the sbb site asks me if i want open or corridor and then the part fm Basel to Paris says to choose no preference or solo - what does that mean

Callen, are you buying first class tickets?
First class is 2+1 seeting (2nd class is 2+2). "Solo" is one of the terms used for the seats on their own (the "1" of the 2+1).

i can get all the way on the sbb website but it won't accept my payment. i know that sbb normally does not book this far out but this is a TGV train and you are supposed to book early/ some of the other trains are already more expensive then what I want . The other websites are more expensive for the same train. the solo was to put into first class and then you got to pick your type of seat (i.e. side by side) I also tried to book it second class which to me looks better than most domestic flights but it won't let me purchase either. i didn't try paypal yet i was able to put in passenger names, sign up for account, pick seats etc but not purchase. i had to walk away and will have to try again.

Is it a credit card issue?
Have you told your bank you are doing a foreign transaction?

If you are trying to book Swiss train tickets on the SBB website for September, you may be too early. Did the SBB website have a note when you tried to purchase tickets about a valid period through something like 18 or 19 June ( up to a month in advance)?

Is there some advantage to buying Swiss train tickets so far in advance?

My credit card had been informed so I knew it wasn't that but I called them anyway and they said that it was nothing on their end. the reservation has to be done ahead bc of the TGV train to Paris internationally requires a reservation and the cost increases as time goes by. Since the SBB site let me go about 10 screens in and gathered travel info about both passengers, direction facing, seat preference selection etc along with letting me sign into to the sbb account, i thought it would let me purchase. but it won't process my payment and the credit card said they had not even gotten a request. thru SBB the fare was 134 thru en.voyages-sncf.com the same exact trains were 143.80 and thr trainline.eu the exact trains were 150.80. I haven't read the terms and agreements for the voyages and tranline website yet.

Some tips about using the SBB website - when you put in your parameters, do the time first and then the date. It has a tendency to change your date on its whim -constantly changing from Monday 18 to Sunday 17 if I had not been paying attention it would have been the wrong dates and not what I entered. Also do not sign in /log in to your account as soon as you get to the website - wait until futher into the purchase process when it prompts you to sign into your account or you won't see all the trains and dates available. I still don't have tickets after all of these days/hours. Guess I will go investigiate these third party site tho I typically like to book directly with the train/airline/hotel etc and not go thru a third party - this time the train will not take my payment. someone had suggested using paypal if it wouldn't accept payment but the sbb does not accept paypal that I saw. Obviously other people have had this problem.

also i forgot to say if you are just trying to book a domestic train only they gray the dates out so it won't even let you select dates further out for those. However since it did not do that and bc the seat on the TGV MUST be reserved that is a little different than trains in the interior.

I never could get it to work and I emailed them to no avail. I ended up booking the same trains on trainline.eu with no fees or upcharges using the same Capital One credit card no problem with the card just the interface with the Swiss website.
The fare was slightly different but I was able to print my tickets at home plus download it onto their ap on my phone and cross that off the list. I did see where seat 61 talked about a special ticket (I think called Swiss transfer or something like that) where you can get certain discounts for connecting to TGV international but it wasn't worth it for me. It might be for future readers so I would check out that seat 61 website and the specifics on that fare.

A couple of comments----

SBB apparently rejects a lot of American credit cards if they do not have the 3-D security layer ( and sometimes even if they do). American Express does work.

For travel entirely within Switzerland, tickets cannot be bought online more than 30 days in advance. For cross-border travel (i.e., Zurich to Milan or Spiez to Domodossola), tickets can be bought well in advance (90 or 120 days) and there is often a good discount price.