Pretty much exactly what Sigoroth said:
Build your fleet around Cruisers, primarily Carnages supported by Devastations. For example:
4 Carnages
3 Devastations
That's 1290 points. Add a Warmaster (on one of the Devastations, which should probably squadron to share that Ld 9) and you have 110 points left to blow. That could be, for instance, 70 points to upgrade the Warmaster's Devastation to a Styx, plus an extra re-roll, with enough points left to upgrade a Carnage to an Acheron, which would leave you with this:
540 - 3 Carnage
380 - 2 Devastation
190 - 1 Acheron
260 - 1 Styx
125 - Warmaster, extra re-roll (on styx)
(1495)
Alternatively, you could go with:
720 - 4 Carnage
380 - 2 Devastation
300 - Desolator
100 - Warmaster
(1500)
Both would be solid, long-range, broadside fleets--which is really what Chaos does in BFG.