I am in my 40's and I can tell you at THIS point in my life I could give a rip what people think of me. I wear a "fanny" pack or whatever you want to call it,
crocs and anything else that makes me comfortable in the parks.
And I will admit I use mine on other vacations where I am going to be walking around a lot. I am going to D.C. and New York in a few days and I am taking it there as well cuz we will be doing TONS of walking with no vehicle and I don't want to be lugging anything around.
So I say do what you think is best and to heck with what others think!