"Spiffy" Casual.

For my date on Sunday, I was requested to wear attire that could be termed "Spiffy" Casual.

I'm at a loss. I can't get a consensus on what this means, and according to several places on the 'Net, "spiffy casual" refers to dress such as "kaki's (sic) and shirt. Clean, nice, but not formal."

Looking at http://www.dresscodeguide.com/default.asp it states that "Smart casual" is collared shirt/polo/tennis, with dockers/khakis.

According to both definitions, that's what I wore for the first date.

I wore a long sleeved black button-down (short collar) with light khakis, and sneakers for comfort and common sense (we walked ~8 miles).

For work...
Our dress code is officially "Business casual" but it is relaxed 245 days out of 250, and we can wear almost anything we want, but a polo/button down and jeans are the implied "lower limit."

So I'm a bit at a loss. Should I wear something similar to what I wore on the first date? And pack something more casual?
She has said she has been having trouble decide what skirt she wants to wear... so I'm thinking that probably means "dress up" more than "jeans-casual."

If my rambling has made any sense, please let me know... I have til about 9am Sunday to get a final answer (though sooner might be nice, in case I need to get my ass out shopping)

Thanks