I also find that using flaps 25 when landing weight is very low, i.e. when landing a 757 PF (package freighter) with not to much load, Vref can go down to about 110 kts. Using Flaps 25 in that scenario brings the Vref up by about 5kts resulting in less pitch attitude and a greater tail clearance.
Bluebird, that's not correct. When using 25 flaps for landing and doing Vref+5, you always have higher pitch than flaps 30. The weight has really nothing to do with pitch attitude since speed is increased at higher weights. At correct Vref+5 your pitch attitude is the same wheather the aircraft is 55 tons or 95 tons.
25 flaps ALWAYS gives less tail clearance but of course Vref 25 is ca. 4-5 Kts higher because of different contour of the wing. When you have 20kts correction on Vref I usually find it better to use flaps 25 because of less tendence to eat up distance few feet off the runway. Ground effect is much less significant at flap 25.
Flaps 25 also saves fuel as well as wear and tear of the aircraft.
I use 25 flaps whenever conditions permit on 757.
767 is a different story. Always 30 flaps there (where I work).