Flying into Venice

Two hours will be plenty of time. I once managed a connection with just an hour, but it was a close call.

Yes, it is fine. That is of course assuming that this is all on one ticket. Just be aware that if you are delayed, the airline will get you to Venice on the next available flight. You may want to verify what options are available by the same airline later in the day, just so you know what to expect if the worst happens.

Should I be concerned about a late departure in Houston that would result in less than the 2 hr layover?

Also, if I end up booking a flight with a connection at another airport, what would be your choices in order and how long a layover in each one should I allow.

Thank you

This can vary and we all have our preferences for airports. If you book all on one ticket, the airline will provide you a “legal connection time” that they consider reasonable, so in the case of a delay they will put you on a later flight. I’d go with the two hour Munich flight and not worry about things that could but will probably not happen.
We don’t know all of your options but if you list them, we can rank them.

The other options were LHR , CDG, and FRA.

Thank you

Many of like to avoid LHR and CDG, but with a long layover I’d have less concern — like three hours or so, but I’d only do that for a huge deal. Frankfurt can be a nightmare and you’d want more than two hours. I think Munich is your best bet!