You'll find the cost of living in both Zurich and Paris more expensive than in Houston, so you will need to ensure that there is a significant rise in your salaries to compensate for this.
Take a look at our cost of living pages for Zurich and Paris to get a picture of the type of expenses you'll need to budget for.
It is important to remember that in general houses in Europe won't be as spacious as those you are used to in Houston.
Buying property in Switzerland is very difficult for foreigners and so most will opt to rent rather than buy. If you decide to buy a place in Zurich you will need to obtain Type C residence permit. While you can get a 3 bedroom apartment for CHF 40,000, a stand alone family home will set you back over a million swiss francs. Read more about buying property on our Accommodation in Switzerland page.
The process of buying a property in France is quite regulated and becomes legally binding quite quickly, so don't rush into things. If you choose Paris, maybe rent for some time first before you decide to buy a place. Read our page on Buying Property in France for a more detailed overview.
Both Paris and Zurich are modern, cosmopolitan cities so you'll find that most people will speak good English. However, in both cases it will help you settle in if you can master a basic level of the local language.
Hope this information helps. Good luck.