While considering the name one could expect a more lavish and decorated bridge, Palace bridge is in fact a simple one connecting the Vasileysky island with the mainland close by the Winter Palace.
I suggest crossing it, as from both sides you'll capture amazing downtown views. We did that walking from the Peter and Paul's fortress to Hermitage.
Another prime attraction is coming here around 1.30 AM. All bridges in downtown St. Pet are drawing bridges to allow vessels pass beneath them.
We did that 2 nights in row, but unfortunately it did not happen so we left disappointed with many others. It seems drawing times are not guaranteed.