I have a set of three cast-iron pans, plus a grill pan. I think they're something like 6-, 8- and 10-inch pans. They all have their uses: The small one works for toasting spices; the medium one for one grilled cheese sandwich; the large one for bacon, cornbread and quesadillas. That's just off the top of my head. The three-piece set is not expensive, so if you have the storage space, I'd go for that. I got a Le Creuset panini pan that has a grill pan and a top grill piece; it's non-stick, so I use that more often than the cast-iron grill pan.
All this will depend on what you and your fiancee like to cook, though.
The trouble with eating Italian food is that five or six days later you're hungry again. ~ George Miller