You sure you won't have any competition for either of those fellowship spots at the one institution you seem to be looking at?
Personally, I think it depends on you. I don't see those "junior faculty" surg path so-called "fellowships" as fellowships, but as just another way for academic programs to milk a suboptimal system -- even if it is perhaps the most effective version of a non-boarded "fellowship" available. You put in your CV you did a "fellowship," when maybe it's really more like a first year of real world experience and perhaps should be counted as such; of course, other surg path fellowships may be no more than PGY4.5 and calling them anything else may be misleading. You're the one who has to decide whether to try to sell your fellowship as a "junior faculty" position (if you can) when you apply for jobs, whether you want or need that additional year of "supervised" general surg path signout, or whether you'd rather spend a year doing something a little more specialized (selective path, or a boarded fellowship) because it interests you or maybe you feel weakest in it and want to strengthen that part of your training.
To be specific about private practice jobs, however, I think you'd need to know what every practice you'd like to land in needs or wants, and that's just going to be variable. I'm not in that side of the business, but personally I'd probably want the core of my group to be good generalists first and foremost, then sprinkle in some subspecialists who also have good core skillz. Cytology just happens to be a little to the outside edge of core -- probably common enough these days that most good generalists see enough to manage it just fine, unless your business is so loaded with cyto that you simply prefer a couple of people to be boarded in it. Ergo, with only those 2 choices I would lean towards doing "surg path".
Personally I don't get doing two widely different subspecialty fellowships, but people do it; everyone I -know- who went that route ended up not practicing one or the other of them, though, or doing so so rarely that it was probably a wasted year in retrospect. But I guess they didn't know what their first job would entail, and wanted to keep their prospects open. Heck of a way to make a career choice.