What do you think of prioritizing my guests first ahead of my girlfriend?
It sounds like a bad idea. Is your girlfriend in an understanding mood?
I hope, I want to treat them all equally.
It is expected your partner would be put ahead of other guests. You don't need to be mean but it is also ok to treat every on equally.
Yes of course.
Plus, it is expected that you treat your girlfriend with favoritism, otherwise people might wonder if you even love her. I am sure you will be able to do both at the same time and treat everyone with equal respect while making your girlfriend the life of the party.