I had a fantastic experience with Viva Las Vegas wedding chapel:
http://www.vivalasvegasweddings.com/They were super nice and helpful, and I think my Elvis wedding + documents + dvd was about $300. The best part was Viva Las Vegas had a live web cam feed, so our extended family could watch from home!
I had bought a 60s white cocktail dress at a thrift store before I met my husband, which fit in perfectly with the Elvis theme. There are usually some nice 50s ones on etsy and ebay.
I got my hair done and it was gorgeous- but I paid about $150 for it, since it was on the strip. If you are renting a car, I would suggest driving a little bit off of the strip for cheaper prices.
After the wedding we had cocktails in the outdoor section of "Mon Ami Gabi" and watched the Bellagio fountain show, then ate at the Paris, but I wasn't too impressed with the food.
My parents rented a limo that we took from the bottom of the strip to the top, stopping at all the hotels that have the shows out front (TI, etc). The driver had it all planned out that we didn't have to wait for anything and we had the best views.
I loved the Flamingo suite that we stayed in, because it looked out on the Belliago fountains, but pretty much every hotel is great.
The only big problem is with Vegas weddings the cost of the photos. I saw someone that hired a photographer to follow them all around the Vegas strip for the wedding, and I wish I did that!