my friend is a sushi chief at Osaka on sahara they have great sushi and a lot of special rolls.
mexican would be
Lindo Michoacan Mexican Restaurant 2665 E. Desert Inn Rd. (Near Eastern) • 702-735-6828
order the fresh guacamole made to order table side and the margaritas are nice.
casual would be
gordon biers on paradise north of flamingo (next to the 24hr starbucks) the garlic frys rock as long as your not going to be kissing later.
there is also firefly on paradise hip evening-night place that has all appetizers.