Both of my best friends (coincidentally) had Vegas weddings and they were both fantastic! I think they both booked the flights and hotels separately to the wedding package as they then did road trips round California for honeymoon, as we did for a holiday each time.
The wedding packages are easily booked through the wedding venues (Little Chapel of Flowers was lovely) and they will do different level of packages so you can tailor to your needs/budget. They each then booked a separate wedding breakfast at one of the many restaurants.
We stayed in the Bellagio the first time and the Palazzo the second, both hotels are amazing (but at the pricier end).
Booked a Virgin holiday, we flew from Gatwick and had a suite at the Bellagio.
Booked a drive through wedding online before we went, at the Little White Chapel. It was stupidly cheap. They picked us up from the hotel in a limo, drove us to go get the marriage licence, then onto the tunnel to stand up out the sunroof and saw our vows. Then dropped us back to the Bellagio where we got shit faced and spent a small fortune on blackjack.
Just be careful of costs spiralling - friends of mine did similar and realised that cost wise, they should have just had a wedding in the UK as it would have been cheaper (but they took 4 kids with them to Vegas)
My sister did this with her Husband and I was a bridesmaid.
Then 2 years later, my friend and her Husband did it.. and I tagged along as the photographer! It was just us 3 and we had an awesome time (they're not coupley and we've been on holidays before as a 3 .)
My sister got married at the MGM Grand as part of a Virgin package deal. We also stayed at the MGM Grand.
My friend got married at the Little white chapel, the same place Britney Spears got married - They stayed in Paris.
I think it worked really well for both couples as you have much less pressure and the day is whatever you make it - In both cases, the brides had their hair and makeup done, my sister got additional baggage allowance for her dress and we all stayed in the Virgin Lounge before we flew which made things a bit nicer!
We did a Limo tour of all the casinos and did loads of other fun things, so it was a total holiday. Despite Vegas being primarily for gambling, I think we spent an hour or so playing roulette and the rest of the entire time in Vegas doing other stuff - Watching shows, shopping, going to see all the animals (Flamingos in the Flamingo hotel, Lions in the MGM etc).
All the friends and family could watch at home as it was live on TV... and despite the registrars doing hundreds of weddings each week, they appreciated every wedding is special to the couple so it didn't feel as if you were just 'one of many' getting married.