So I stayed at Encore last year for CES and the place had just opened. Didn't have a great experience. They lost my luggage the first night when I left it with the bell boy, checking out was a nightmare, ordering food and having basic things in the room (like a pen) proved too difficult... but I must say they redeemed themselves this year.
I stayed in the tower suites this time around for CES and would highly recommend it. The suite is huge... 2 bathrooms, a massage room, living room, bedroom... way more space than I needed. The staff were very sweet, the concierge was great with reservations and checking out was very easy. The separate entrance is key if you don;t have a limo because it makes getting a cab much easier (and you avoid the ludicrous lines that exist at the main casino entrance) and check out is much faster.
The gym fee is a little ridiculous but that's just standard Vegas so it's not specific to Wynn/Encore.
Last thing - one day the maid threw out bags that I had left in the middle of my bathroom... she thought they were trash. Except they contained the shoe bags and receipts from several pairs of beautiful new shoes I had bought. She threw them out by accident. Obviously I was pissed... but they were very professional dealing with it and went back the store and sent up 5 sets of Louboutin and Sergio Rossi covers after they realized what had happened (and who am I kidding... I wasn't going to return the things :) Throwing out the bags - not cool - but the way they dealt with it was very professional and very much appreciated.
Overall, I like Encore more than Wynn and it is definitely one of my go to hotels when i go to Vegas.