I agree with Luci, you need 4 days minimum IN Vegas, it's too far to travel for anything less than that.
Helicopter companies - Both Papillon and Maverick are highly rated, just price both up for when you want to go and book the cheapest!
In my experience, lastminute aren't great for Vegas hotel deals. You should be able to get a much better price by looking independently. Plenty of us on this site can give you some pointers on where to look, in fact, just search on this site for 'Vegas' and you'll see loads of tips and suggestions.
Cheers,
TC