Vdara has a perfectly reliable Wifi connection for the purpose you describe. I've done the same, including extensive video calls with or without VPN to a corporate network.
I also seem to remember Wynn to provide a good wifi connection - and they have a very comfortable desk/chair in their suites. Many of the 'free internet connections' included in the resort fee seem to be wired - which doesn't always work out well, depending on your machine (I use a Mac Air without a port). You could always connect your own wifi router if you are staying in one of these places - you can get inexpensive ones at Target etc for around $20.

Essentially though - my recommendation would be to enjoy Vegas instead of spending too much time working!