I never played 3k before to be honest, but in general in 2k or 2.5k a list would look like this:
Apothecarion Detachment (1-3 models, depending on how many units will be spiced up with one)
2 small Recon sniper squads
1 big Recon 'melee' squad (for scoring purposes)
2+ units of Vet Tacs
Rhinos all around
1 unit of Destroyers in a dedicated Proteus.
Since one cannot deploy heavy support units in LRC, lots of Dreadnoughts are the way to go here.
A fact that sits well with me, since another of my fav RoW would be Fury of the Ancients which is barely playable.
Some Contemptors (& variants) deployed, and several more deepstriking in pods. I don't own a Leviathan, but deepstriking one would also be plausible here in theory.
On occassion, I bring an allied detachment of two Knights, depending on the scenario and if my opponent brings Superheavies / Lords of War.