The SNCF often offers train/car rental combos. I don't know if they have one for the Loire (not Loir

We plan to visit Versailles for a day (2 landscape architects in the group!) and would also like to tour the Loir Valley for a day to see some castles and a village or two. If possible, we may try to squeeze in a visit to Vaux le Vicomte (but that may be too much for the day)
I read references in other posts to train ticket/ car rental day trips from paris, where you get round trip train tix from paris and there is a car rental hotel discounts for the day waiting for you at the destination train station. I cant seem to find any links online to see prices, terms and conditions, hotel discounts make reservations, etc. (i want to be sure we can get a car seat for the little one)
Any advice out there on doing this? Which station should go to? are we better off getting out of paris for couple nights and staying the area? With the toddler, switching hotels etc, may be problematic, and we are already paying for the 7 nights in the paris apartment even if we stay elswehere for a night or two.
We would like to do one other day trip out of paris: Somewhere around the Loir Valley. folks on these and other forums have mentioned taking the train to Tours and getting a car there for the day. At the end of the day you drop the car off back at the train station in Tours, and get a train back to paris.
You can go to the Loire region and do ch teaux and/or hotel discounts wine tasting tours. The TGV will get you to Tours in an hour. You want to arrive in Tours Centre, not the train station Saint-Pierre-des-Corps. The tourist office is right across from the train station and that is where you'll pick-up your tour. Here is the weblink for the Tours tourist office. Click the tab on the left that says "Excursions" and you'll find all the info you need.
If you decide on this you'll need to use the TGV website to buy/reserve your tickets. For info on these trains use the website www.tgv-europe.com for schedules and prices. Don't forget to uncheck the box marked "Direct Trains" to see all possible options. If the TGV site redirects you to the RailEurope website then try again and enter "Antarctica" as your ticket collection country. Other countries may also work but just try to find a country that doesn't get you redirected to RailEurope. The RailEurope website often doesn't show all the trains and generally has higher prices but you can check just to compare. You can buy tickets up to 3 months in advance and the earlier you buy them the cheaper they will be. The discounted tickets are known as PREM tickets but these are non-refundable and can't be exchanged.
I do not know of any service that would arrange the train and car rental for you, and I imagine hotel discounts that they would do this only if there was an organized tour at the destination. You could try and look for tour groups, and then identify the ones that offer train and car included.
You can also very easily arrange transport yourself, by buying train tickets, either in person or in advance by internet, and by reserving a car at the train destination. We are doing this in England this summer for a day trip to Stonehenge and Avebury, and doing a similar arrangement for a 3-day trip to Normandy from Paris. If you are nervous about buying train tickets, you can search the board for "France train tickets" or some such. We are renting a car through Europcar, and they do offer all manner of child seats.
The SNCF often offers train/car rental combos. I don't know if they have one for the Loire (not Loir, that's a different river), but I would guess they do, as it's a major tourist attraction. You can check out their offers on the same site you use to book trains: www.voyages-sncf.com (and maybe www.tgv-europe too, though I never use that site).
The tgv-europe.com site is just the English language version of the voyages-sncf.com site. If you click on the British flag at the bottom of the sncf site it brings you to the tgv-europe site. On the tgv-europe site there is a tab on the top that gives a "Train + Car" rental hotel discounts option, though I've never used it. If there are 4 adults it may actually be cheaper to rent a car for the day if you go to the Loire vs. the cost of 4 adults paying a per person cost on a tour but you'll have to compare to see which is cheapest.
There are also day-long coach tours from Paris and van tours from Tours - but I don;t think I woldattempt either one with an infant. Even if they allow this (and many tours have a young child age limit) - what do you do if the baby doesn;t fell well and gets fussy. You and s/he just suffer for many more hours? With a car you more esily address this kind of problem.