Are we still talking about post-Reaper War shenannigans? Jakarta wouldn't understand the concept of "vacation" if it smacked her in the face. She's a Spectre and an Alliance soldier. Her duty is to put herself, bodily and with pointy guns, between evil and the innocent, until such time as either evil or the innocent cease to exist. Since neither is likely any time soon, she'll probably take five minutes to kiss Ash senseless in a bold moment of victorious glee, and then get right back to the business of taking down slavers and negotiating ceasefires and all that other fun Spectre stuff, with Ash and Garrus and Grunt at her side if she can manage it (the first two because they're family and there's no one else she'd want at her back, the third because she's realized she's his apparently his mom and feels an obligation to make sure he grows up right).
Varick would do the same for completely different reasons; she's out for redemption, and will never believe she's earned it no matter how much good she does, so she can't quit or stop putting herself out there to save the universe either. She would probably take some time on Intai'sei with Thane, though, and not go back to Spectreing until he dies.
IDK about the rest of my Sheps. Kuan Yin* might retire with Liara and have lots of blue babies, though. She's the type to keep her word.
* @OG: Yeah, I found a bunch of different romanizations of the name, and the two-word K construction seemed to best convey the impression I wanted for her, at least to my Western ear. I spend a lot of time on baby name sites for my own writing, so at any given time when I start up an RPG I have about thirty names with potentially appropriate meanings written down somewhere that I can use. ("Jakarta" was pure Mass Effect from the start, though; as soon as I read in the Codex that Alliance cruisers are named after cities, I knew my little Spacer baby was going to be as well, and from there it was just finding the right city in her nation of origin).