If you haven't already bought the CPU, then I would hold off for a few weeks if possible until Sandy Bridge (LGA 1155) releases.
Even if you aren't ready to be part of Intel's beta testing of the platform you'll most likely see a good reduction in P55 mainboard prices as vendors look to shift inventory. Intel has already stated that it intends to aggressively market the P67/H67, and with higher clocks and improved architecture (around 10% increased performance clock-for-clock over Lynnfield, 25-30% improvement at the same pricepoints) mainboard manufacturers and etailers are likely to slash prices on LGA1156 boards.

With the present pricing in effect I would look at:
Gigabyte P55A-UD4P
Asus P7P55D Deluxe (incredible pricing for the feature set but lacking SATA 6Gb and USB3
ASRock P55A Extreme4 (very good feature set)

All three boards have excellent PCIe slot placement allowing for breathing room between graphics cards.