Everyone knows that Rory parallels her mother Lorelai. If you didn't know that then maybe you should watch it again. I recently finished watching Gilmore Girls for the umpteenth time and caught many parallels between the boyfriends that each of the women have throughout the series.
The obvious one that I'll start with is Christopher and Logan.
Christopher comes from a wealthy family which he rejects. Logan's family is also wealthy. Logan is more reliable than Christopher and less absent minded but he still has his moments. Both men deeply love their Gilmore Girl, respectively, but neither relationship ever pans out. Christopher cheats on Sherry with Lorelai and Logan cheats on Odette with Rory. They're both reckless, but mature as they age, and are now (presumably) both baby daddies.
Aside from being uncle and nephew, Luke and Jess have a lot in common. When it comes to talking to Lorelai or Rory, respectively, they both tell it like it is. They say what needs to be said, not what the girls want to hear. Luke helps Lorelai keep her life on track whether it be running the kitchen at the inn or fixing her house or just being Luke doing Luke things. Jess keeps Rory's life on track by getting her to go back to Yale and write a book. Their love for their respective Gilmore Girl lasts for years-- even with others getting in the way. They're tolerant of the shenanigans that come with being with a Gilmore and they care deeply about them.
ASP may say that she created Logan to be exactly like Christopher but we cannot deny that he also has some similarities to Luke. No matter what, Luke will drop everything to help Lorelai when she calls. This is very similar to how Logan does the same for Rory. When Lorelai is upset, her first instinct is to call Luke. When Rory is upset, her first instinct is to call Logan. There is a ring but no wedding, well at least not until the reboot. And just to be silly, their names both start with L.