I recently purchased some denim shorts for my holiday - unbelievably they were the only item of denim clothing i didn't already own (i say this but thinking about it now i do have a few pairs of denim shorts just not any exactly like these!).
I think shorts tend to be more flattering if they fit looser around the thigh and not to tight around the waist/ hips (NO muffin top) also they are more comfortable that way and if they are comfortable you are more likely to wear them.
Mine are from Zara and fit as described above. I'll be wearing them with a looser fit top, possibly over a swimming costume. There are LOADS of denim shorts around - some fit higher around the waist like Mom jeans (good for pot belly hiding), some fit looser, longer, tighter, shorter... here are a few i've shortlisted.