How to deal with classes that I must cancel due to conference travel?

I do it like this:

1. Try to let a colleague* take over. This almost always works with 'standard' classes (intro to statistics, this kind of stuff)
2. Plan the classes in such a way that the students are busy with something else in this week (e.g., data collection), so that a plenary meeting is not necessary.
3. Cancel - but if I would cancel more than one meeting of a course, I would probably get problems with my department.

* we don't really have the concept of a TA here, you are either teaching (then, you are a colleague) or not - so 'colleague' also can include graduate students that might be referred to as TA in other systems

(context: Europe/Netherlands; social sciences)

The first step should be to ask what is usually done at your institution.

Currently I can reschedule lectures when it's really necessary.

At a previous I have written slides for my TA to give. I also covered a lecture for a colleague, from their notes. In this case there was a minimum number of hours of instruction for the course, so missing any would have been a problem (I did cancel one, but in unexpected circumstances).

Adding on to @damian' answer, another suggestion prepone your classes of that period by swapping sessions with your colleagues. This would also require cooperation and understanding from your colleagues.