The answer to the former is no, since all the "vegan" option on the Wynn site navigation does is take you to a few pictures of what are evidently vegan dishes from unidentified restaurants. The website, now in its third incarnation, has been subject to controversy at every turn, opening with an overly-complicated, perpetually-in-motion headache that for the longest time greeted readers with a personal apology from Steve about how long it took to download.
Fast forward to a month or so back, and a new site was launched. We wish we could say it was improved, but the VegasChatter blog seemed to speak for many of us when they wrote that the "Wynn's new website has us scared and confused."
Thankfully, that aberration didn't last long, and yet another new site was launched a couple of days ago. While it has slightly more information than the middle version (which listed no lounges or bars at either "Wynncore" property, for example), there are no vegetarian/vegan menus listed.
Why this might not be so unusual at other venues, around this time last year Steve Wynn announced, with much fanfare, that he'd converted to veganism and was insisting all the restaurants at his properties, including SW Steakhouse (we would've loved to have been a fly on the wall at *that* meeting) were henceforth to offer vegan dishes. Hence, we would have expected more prominence given to vegan menus, if it weren't for a small whisper from gossip columnist Norm! in the R-J, of which we've heard nothing more since, we hasten to add, that Steve had fallen off the wagon and was no longer a practicing vegan. Who knows?
All that aside, we're happy to inform you that we can address the second part of your question and provide you with a link to all the vegan menus at Wynn and Encore, as kindly supplied by the PR department. We're assuming there are variations in the dishes from time to time, but these should give you a good idea of what to expect. We hope you and your wife will both find something to your liking (Bartolotta is a great restaurant and a Top 10 pick in Eating Las Vegas, in which you'll also find a "Special Diet" section," which should help with other veggie-friendly suggestions around town).