One pound of live rock per gallon would provide an ideal amount of biological filtration for a 150, and having a sump in the system would help greatly. Having a sump would leave you open to the greatest amount of choice of skimmers and provide space for heaters and any chemical filtration you might use.
The Remora and Bak Pak skimmers suggested in the previous post are both great skimmers, but would be very undersized on a 150g. If you don't mind fiddling around with a skimmer until it's tuned right, my suggestion would be a Beckett-injected skimmer (Precision Marine Bullet, Aerofoamer, My Reef Creations, Barr Aquatic) or an AquaC EV series skimmer (spray induction). Once these skimmers are tuned in, they produce nastier skimmate than needle-wheel skimmers in my opinion (Euro Reef, ASM). Though the Euro Reef and ASM skimmers aren't bad choices if you want a "set and forget" skimmer.