I was wondering what are some differences and advantages on playing as an opposite gender. I'm a guy and I've never really made a female character on new Vegas. Well, not for like 5 minutes...

I was wondering if there were any disadvantages and advantages of playing as an opposite gender of myself. I was thinking a doctor;)

There really are none, here are a few:
As a girl you cannot fight in the arena at the fort, as a guy you can
As a girl you can sleep with Benny and kill him in his sleep, as a guy you must fight him in the lobby or at the fort (if you have high enough speech I think you can fight him alone)
As a guy you can get free repairs from the guy at the Mojave outpost (Only if you have the required caps and only once)
Those are really it...

I always start Fallout as a male (kinda like playing as myself) then second time through i play as a woman, It just gives me the freedom to be someone else completely, maybe its just the way i work but currently the woman is far cooler than my original character lol i dont mind checking my woman out from behind as she slowly walks

Despite a few minor inconveniences for both sides, I just stick with male since, well, I'm a male.

I believe you can do that as a guy too, if you have the confirmed bachelor perk...

Ah yes, the hilarious Confirmed Bachelor perk. What makes it hilarious? All the 'HELP! I THOUGHT CONFIRMED BACHELOR MEANT I WAS A PLAYER, NOW MY CHARACTER IS GAY!' threads. Good times. Good times.

I noticed that female characters get a lot more attention and six scenes.
But I have to admit that I almost unconditionally play as a female in RPGs. Yeah, sue me.
The reason is not aesthetic. The reason is that my male characters - always - end up total bad guys, who kill, ignore and assist villains. It just feels more natural to play as an evil male, but it lost its shine in the long run, so I tend to play as female which has much less moral restrictions for myself and allows me to play a more positive and eventually a more rewarding game. This syndrome has been especially bad in BioWare games which include a lot of grey-shaded black/white decisions.

I too am a male that almost exclusively plays female characters in RPGs

but really the only reason is that character creation has gotten too good. When I try to make a male character I want to roleplay it as myself, which back in the day wasn't an issue since you just picked one of a few pregenerated faces and bam, start the game. But now with face generation, even as dated as it is using the Fallout3/Oblivion/etc engine, I cannot get the face to look enough like mine and it creeps me out as if I looked into a mirror and saw a different person

so I make an attractive woman and just roleplay ingame-decisions as normal