It's like you said: according to your priorities. I'm not saying your priorities should be different, but how often you visit them is inherent to who you are or are not and how you were raised.

I won't beat around the bush: I say this because I'm in the same situation you are. I live in Boston, my parents live in Virginia, my brother and best friend in Florida, half of my family in New York, the other half in Europe. My friends are even more spread out; I make them in the strangest places and my participation in many international themed student organizations in the past have contributed to this problem. I have a good chunk of people I know in California, Colorado, Taiwan, Prague, England, etc etc.

And similarly, I have a girlfriend. She's not the love of my life, but we spend a considerable amount of my free time together. The only two differences is that:

1) Seeing these other people is very important to me. They are the essence of my life in most respects.

2) I grew up this way. I spent most of my child hood living very far away from my entire non-immediate family. Only travel and expensive calling cards (then chat, and finally Skype) could solve that problem.

That is why I spend a considerable portion of my financial and time resources on seeing them. And I've found a person that understands that and lives with the fact that I'm gone frequently, or she comes with me. She knows that it's really important to me.

Now, I am not saying that you are a horrible person for not seeing friends and family more often and that I'm a shining beacon of commitment to them. In fact, the truth may be completely different: that you have matured past the need to see these people so often, and I simply have not gotten over the fact that people's lives go on and it's the reality of life that you will miss the parts of their lives no matter how hard you try.

Either way, what matters is that you are not violating your own beliefs on the matter. If you are content with how much you are seeing them now, that is perfectly okay. There is no standard that's correct here. Are they giving you shit for it? That's still fine. Your parents raised you, but they should still have reasonable expectations. And they can visit you themselves if they really wanted to; in most cases, they are the ones better equipped to do so anyways. Everyone else who complains, you really owe them nothing anyways. Your past friendship is what ties you together, not some debt you feel you have to keep paying off.

Now if you actually do want to see them more often, then you simply have to recognize it as a problem and work on fixing it. Maybe you discuss it with your girlfriend, or set a plan to move closer to all of them at some point. The important thing for this case is that you don't lie to yourself and simply tell yourself that it's okay to dedicate more time to your girlfriend when in reality the problem is something else, like not enough money or a girlfriend that's trying to convince you otherwise (saying nothing of her in reality; I know nothing about her).