Small ships may keep the players involved in that they're crewing each station, but they also have the possibility of making them less involved because those ships aren't effective in some situations. And of course automation and simplicity makes it possible for a small crew to man a very large ship - modern supertankers and container ships have crews of twenty to fifty people (lower if maintenance is mostly done in port), for example.
To a large extent I'd say it depends on what you want. I think [MENTION=177]Umbran[/MENTION] is quite right to suggest that the "science" in science fiction means extrapolating from modern equipment is desirable, but FTL drive systems simply aren't part of that - even fusion power isn't really part of that just yet. And I rather suspect that there aren't that many people familiar with the technology to produce sensible values, the smallest nuclear powered submarine being only 400 tons (though that was an unmanned experimental design; the smallest manned ones are the French Rubis class at just under 3000 tons). If your drive systems don't require a huge amount of power to make FTL speeds practical, then you could use much cheaper and smaller technology such as Hydrogen Fuel Cells. If people want spacecraft that are cheap commodities like modern cars, then pick options that justify that; if you want them to be more like private aircraft, use that; and if you want travel to depend on buying tickets, then pick options that support that - massive and expensive drives that mean travel between planets is only possible on really large ships that are expensive even for governments and beyond the reach of individuals, say.