Las Vegas is a long way from the Grand Canyon by helicopter. You'll probably want to combine an airplane tour between LAS and GCN with a helicopter tour which departs from the GCN area. For the airplane tour portion I'd recommend Scenic http://www.scenic.com/ They have the twin otter aircraft which is powered by two P&W PT6 turboprop engines which are much safer, and more comfortable due to their bleed air for heating and cooling, than a piston powered airplane. Scenic will provide all of the hotel transfers in Vegas and ground transportation at GCN.

I can't tell you much about the helicopter tours but there are several helicopter operators at the GCN airport and just North of the airport in town. There are probably package deals avaialble that combine the two tours.

FWIW, I flew about 400 LAS-GCN air tours for another airline (that no longer operates in that area) back in 1990.