Whilst Mostar appears to have been traditionally been a day trip to visit from either Dubrovnik or Split in many posts, we choose to stay overnight in a visit in October 2024.  We stayed in the old town and our bedroom window had a view of the Bridge which was wonderful.  The old town is very commercialised with mass UNESCO inscribed awnings hanging over each of the shops along the old cobblestone roads.  The commercialisation took a bit of shine of the site, but it was pleasant to wander the streets and appreciate the old town itself.  I would recommend an overnight at least as this was you can avoid some of the large crowds early in the morning and late in the afternoon.  It also allows you the opportunity to visit Blagaj Tekke on old Turkish monastery a short drive away which is currently a Tentative UNESCO Site as well.  Whilst I could appreciate the sites worth, the commercialisation and the fact the bridge itself is a reconstruction took some of the gloss away from the site for me.  Bridge diving / jumping has seemed to create a small economy for local jumpers, who offer tourists the opportunity to pay them money and when they think they have enough, jump into the river below.