For those of you short on time - there are many companies offering half day trips to Grand Canyon via helicopter. Note that these tours go to an area outside Grand Canyon National Park. For information about visiting the national park, see the "Grand Canyon National Park" article.
Prices do vary and it is important to find out what kind of connecting transfers are involved. Cheaper helicopter/plane tours may involve long bus rides to some terminal further away and an endless wait before you board the aircraft.
Look Tours is a booking agency for Sundance Tours and there are savings of about US100 if you book via Look Tours than directly with Sundance Tours. Their Grand Canyon Helicopter Tour lasts just under 4 hours door to door. They offer this tour several times a day so you can choose the one that best suits your timing.
You will be picked up in a stretch limo at the appointed time and brought to the Sundance terminal where you will be weighed in. Don't expect to have the limo to yourself, that's how they pick up all the passengers for this tour. It takes about 5 minutes to drive from the Strip to the helicopter terminal, which is right next to the airport.
Each helicopter only takes 6 passengers - 2 in the front row and four at the back (which makes it a raw deal for those sitting in the middle at the back). You will be given headphones and the pilot will give you a short introduction and also play a recorded narration as you fly over certain places. All your comments, the narration etc. will be recorded, along with a video of the scenery below taken from the helicopter as you fly there and back, so you have the option of purchasing the DVD of your entire trip when you get back to the terminal. They will also take a photo of you, just before you get into the helicopter and this will cost US17 if you decide to buy it. The VCD will definitely cost more.
On the way there, you will fly over the Hoover Dam, Lake Mead and finally reach the Grand Canyon. After flying about 45 mins, the helicopter will land, not quite on the canyon basin itself but on a plateau near the basin where they will set up foldable tables and benches for your champagne picnic lunch. 
The descent is quite gradual and takes about 5 - 8 minutes so you do get to see the Canyon at "rim level" and lower. Most of your best photos will probably be taken during the descent and ascent.
The inclusive picnic consists of a turkey sandwich, apple, crudites, a large chewy cookie and some soft drinks, and, of course, champagne served in plastic wine glasses.
From experience, most time on the ground will be spent taking photos/videos/exploring the area on foot rather than having the picnic. You can take whatever you cannot finish eating back with you. The pilot will stick to the schedule and the flight will take off punctually after half on hour on the ground.
It will take about 45 mins to return to Las Vegas and the trip will be rounded off with a fly-past over the Strip and the old town Freemont area. Although this tour is not cheap (US300 per person), it is great for those who are short on time and you are able to visit the Grand Canyon in half a day.