Those cute, short little shorts that are advertised as “running shorts” don’t work for me. You know the kind, they are loose and have just a few inches at the inseam. My thighs are too wide and rub together and create horrible chaffing. Hence, I have known for a long time that I need tight-fitting bottoms for running.
There are three general lengths for running tights – long, capris/mid-calf, and above the knee. For the two longer versions, I find that they fit best (ie don’t keep falling down) when there is a tie at the waist. The problem is that the knot always seems to be on the inside and on longer runs I end up chaffing around my belly button. I have just dealt with this for a long time, sometimes using something like Body Glide to protect my skin and at least avoid some of the chaffing.
It recently occurred to me (a real duh moment) that my tri shorts, which are above the knee (about a 4-5 inch inseam) do not fall down around the waste, and do not have a tie that causes chaffing. I happily found some tight-fitting running shorts (only difference from tri shorts being that there is no padding for the bike portion of tri) at a thrift store! Excited to realize that this is my answer for long summer runs!