Lots of wisdom around specs strategies, here. I'm thinking 3-4 is a good number for rotation, and if the prescription doesn't change much or the frame is fairly classic, the collection can grow.
There seem to be a few Fabbers who are loving the red frame trend, and others who are embracing the white trend, with tortoise a tried and true.
My favourite glasses of the past were a round pair of metal Laura Ashley frames in rust coloured metal, and some half frame oval ones in a dull white gold/pewterish metal. I was forever getting them straightened, though.
Usually I don't pay attention to specs trends until I need them, but I've had a heightened awareness these past 6 months and noticed the following...
-squared shapes are hugely dominant (vs round, aviator, and other styles)
-deeper lenses are coming back (but not oversized)
-shallow ones are still strong
-plastic frames outnumber metal
-dark/high contrast far outnumbers lighter colours or low contrast frames
These are just general observations from an admittedly limited selection of specs shops in a smallish northern Canadian community. I'd love to here observations from bigger more metro comminities.