I think oil pastels and pencil is a good combination for travel. I like to use pencil on top of the oil pastel as well as oil pastel on top of pencil. Makes the colour look less like it has just come out of the box. Generally, a hard, HB or harder pencil is what I want for this kind of work. I love the texture as the pencil goes into the oil and the paper to make a depression and also the flecks of oil pastel making little colour spots across the paper.