The tension I'm used to these days is 10's in Eb standard on 25.5". I'd probably tend to use the same on 24.75" too. I currently have 11's on my Les Paul just for the fun of it but that's proving a little too stiff for me. I change out the 46 for a 52 for drop C#, and I use an 11-56 set for drop B.
Anyway, as for the question in the thread title; Do you bother changing string gauge if you're only dropping half a step, or do you just deal with it being slightly looser?
On one of my guitars (25.5") I've tuned down to D standard (from Eb). I've used a set of 11-49, and it's just that bit too stiff. I know that's not very big, gauge-wise, but with me it's not that it's impossibly hard to play or anything, I can get on with it quite fine, and find whole-tone bends easy. But it's just a feel thing. I like big bends, wide vibrato, and I find pinched harmonics just don't quite have the same oomph and character.
I know you can get "half" gauges with D'addario these days (9.5, 10.5 etc) but I prefer not to get used to specialist items, in case I'm in a bind and need to grab something from a local store or something. Plus I prefer to grab multipacks and keep things simple.
EDIT: Just in case anybody suggests it - I fucking loath hybrid sets
I used to care, but I really don't anymore. As long as it's within reasonable margins of tolerable I'll take it.
I use D'addario EXl 116s (52-11) on 24.75" stuff for DGCFAD, but it can do drop C tolerably, drop C#, Eb tuning, even B.
I don't play with ultra low action either, so there's that. That shit sounds bad.