I need an idea for what to do on my birthday?

I am in my twenties and my husband is in the military so I am far from family and close friends. My birthday is coming up and my husband will be away training so I am here alone. I still want to have fun so what are some ideas of things I can do that is fun and would still be enjoyable if I did an open invitation for ladies I may not know well. I am nearby large cities (vegas, los angeles, san diego) so pretty much anything and anywhere is an option.