When we are through with the day early, I have finished the next days travel plan, don't feel like going to bed yet and we night want a break from what books we are reading, we may play open gin rummy. This is harder than you think. Seeing the others cards does not mean you will make the right choices.
In case we have more than two, we have Qwirkle. This is sort of like Mexican Train, but without a whole set of dominoes. It only requires a flat place and not a very large one at that. The travel version is a soft pack and can be stored anywhere.
We don't carry a TV, I do have a laptop, but we don't usually try to bother with electronic entertainment.
Matt