I think for some folks, it’s still a temptation to just buy the matching set of bath towels, hand towels and bath mat. But, interesting, intentional design is all about the details, and matchy-matchy just has to be avoided. Bath linens are a great place to play with pattern, texture and color. Unlike paint or wallpaper, towels are an inexpensive, non-permanent addition to the room. Really, towels only last a year or two with kids, so you can trade them out in no time at all.
I did a little online shopping and found some fun bath linen combinations that are far from boring. Yes, there are lots of neutrals (you know I love grey!), but with fun patterns and fringe details boring is not an option. 
- Bath Towel // Hand Towel // Bath Mat
- Bath Towel // Hand Towel // Bath Mat
- Bath Towel // Hand Towel // Bath Mat
- Bath Towel // Hand Towel // Bath Mat
- Bath Towel // Hand Towel // Bath Mat
- Bath Towel // Hand Towel // Bath Mat
- Bath Towel // Hand Towel // Bath Mat
Is there a combination you like best? I think I want #7 in my bathroom, I already have that hand towel. And #2 could be fun for the main bathroom, that my grubby kiddos use.