Eh, it never would've worked out between Sam and Frodo. As my friend so eloquently put it when we were talking about Sam's kids: "He must've been busy (to have that many kids) and it wasn't with Frodo!" Mainecoon also has a good point about the whole issue in her fanfiction
Sam Gamgee Woke Up Gay. (Trust me, this one's definately not what it sounds like.)
I don't see why everyone thinks Frodo needed a wife. One can be perfectly happy as a single; I mean, look at Bilbo! (True, he was a bit crazy, but that's not my point!) I'm happy being single and I always pictured Frodo as being the same, once he got to Tol Eressea and received his healing.
Can't really picture a hobbit with an elf...or their kids for that matter...