Haha.. I hate it when people say "be careful going there or there it's bad neighborhood" or something like that.. Because when I go there then I'm all scared and paranoid lol... but it turns out it's always totally chill
I havent been to vegas but it's what I'm planning on doing sometime this year hopefully.. but about having fun solo... I found that at any tourist areas in any country its always easy to meet new people to hang out and have a good time with... especially if you go to a hostel or share an apartment with others.
But if it's not tourist area then I think it's suddenly really hard to meet new people.