Sounds like a great shape tank. The 48X24 footprint will be a breeze to aquascape, and the shallow depth will make it very easy to light. To be honest, it seems perfect for clams and SPS. 250W bulbs will be plenty of light; in fact, with that shallow of a depth, you could run fairly low PAR bulbs and still get alot of light. This will give you more flexibility with color temp bulbs.

I don't know if you already have reflectors, but that size tank is perfect for the lumenarcs.