There are other F&B outlets in T3 at LAS that are available if you don't want to spend time in the lounge. I can't speak to the quality of the food etc. as being a local I tend to eat at home before heading to the airport, plus we usually drink in the Amex Centurion Lounge before heading over to T3 just in time to board. In terms of duty free shopping there's one reasonably sized shop, yes. Never been in it so can't comment on selection or prices. Anything purchased there is delivered to you at the gate immediately prior to boarding.