Older runabout types would also be fun to visualize. Something fitting the TNG Type 7 shuttle style for mid-24th century (possibly the big warpshuttle in "Skin of Evil" was actually an older runabout?). A TOS movie design - I have no real ideas for this.
And a TOS design... The craft seen in "Way to Eden" would be a very nice TOS runabout, or perhaps slightly pre-TOS so that civilians have now acquired these surplus models. Older, clumsier tech, so it's bigger and has real trouble landing (but perhaps it can still manage?).
I officially call this a "heavy shuttlecraft" because "runabout" IMHO refers strictly to the TNG era class of vessel. My TOS version is a bit smaller, but I guess it's similar, except it's not modular.