Trains are completely non smoking and have been so for several years.

Second class will be fine at that price difference. I only go for 1st class tickets when the difference between the two is 10€ or less.

All trains in Europe that I know of are non-smoking, including the Thalys Paris-Brussels train. If seat comfor is not key then there may not be enough difference for you. But there are significant differences always between first and second class (this is why zillions of Europeans pay more to go in first class!) - 25% fewer seats in same-size train car means bigger seats with more leg room and often more empty seats in first class - yes I can usually find an empty seat near me to put my luggage in rather than perhaps fending for space in already overcrowded overhead luggage racks in 2nd class (but if you board in Paris earlier than most then that will not be a problem).

Thalys first class seats do provide a substantial meals with wine or beverages of choice at your seat as part of the ticket price.

ditto for the Brussels to Bruges train though no free food there.

If going to Bruges note that taking a French TGV via a change at Lille-Flandres to regional train to Bruges is just as quick - 2.5 hours or so and can often be cheaper than the often much more expensive Thalys trains - go to www.voyages-sncf.com and seatch for cheap Paris to Lille-Flandres tickets - the Lille to Bruges ticket is a flat fare ticket and there are no seat reservations even possible so can even buy that in Lille before the train.

Thalys trains have a Byzantine fare structure with many tiers of tickets sold in alloted numbers - early birds willing to book up to 4 months in advance can get really cheap tickets and note with Thalys the ABS or All-Belgain-Stations fare which allows you with your Thalys ticket to Brussels then to hop on any train within 24 hours (could be 48?) to Bruges - this ABS fare usually I believe cost a few euro extra but is much cheaper than a normal Brussels-Midi to Bruges fares. www.thalys.com for Thalys fares.

Great sites for great info IMO on these trains and European trains in general - www.seat61.com; www.budgeteuropetravel.com and www.rickstevees.com.

Paris-Brussels
Thalys: I have done both ways, 1st class when I found a discount.

Luggage space: 1st class tends to have more space near your seat. 2nd class has less space overall around your seat and seem to be favored by families with a lot of luggage, both of which may require you to use a luggage space at the end of the car. The last time, I sat near the luggage area in the 2nd class so it did not make difference that I had to use the storage area. Before I hit "buy" button, I though I was given proposed seat assignments, so I could double check where I would be sitting. If you are traveling light, this matters less.

At Gare du Nord: The 1st class cars, at least the times I used, were the ones nearest the station (tail). The 2nd class cars are at the other end (head) of the train. Thalys trains tend to be very long, that means a lot of walking to reach your car.

Meal: Yeah, 1st class was supposed to come with meal on board, but I seem to hit those trains that run out of food. The conductor just came around and told me to complain after I get off to get compensation.

Brussels - Bruges
The issue I found with 1st class here was whether I could get to it. There were two trains I could use. One had 1st class in the middle of the train while the other one had them way at the end of the train. I just missed a train with 1st class in the middle, so that was where I waited for the next one, but lo behold, the 1st class was nowhere in site on this long long train and people were pouring into cars, so I just hopped onto the nearest 2nd class.

Indeed some domestic trains may not have first class per wit Greg's experience. I have ridden zillions of Belgian trains however and never saw one without first class except for pure commuter trains in the Brussels area - but I have not been there in a few years so things have changed.

For a short notice trip you may well find the TGV routing via Lille to be cheaper and again just as quick - simply because on short notice most if not all cheaper Thalys tickets may be sold out but the TGV may still have discounts available as that route is not nearly as much in demand as other TGV routes in France and even regular fare is reasonable and much cheaper than regular fare on Thalys train. Highly consider that route IMO - be sure to compare both and take cheapest as IMO all other factors are equal.

Thank you for all your advice. I end up bought the 69 Euro first class tickets because there was no more 39 Euro 2nd class tickets. It is very strange, the semi flex 2nd class ticket is same price as the semi flex 1st class ticket!

Just curious as to which route you took - Thalys for 69 euros or TGV train - assume Thalys and in which case the extra for first class even if 39 euros were available is good because the meal itself is worth a lot IMO.

I took the Thalys from Paris Nord to Bruxelles Midi. I try the TGV but the website direct me back to Thalys. At first I thought I hit a wrong tab but I try it twice and it keep direct me back to Thalys. Anyway they assigned two good seats for me and my husband so we are happy with it. Thank you for introducing me to seat61.com. It is a very helpful website.