My wife's current style is similar to the shortest one in the pictures but with the top shorter and less tapering in the back.  She now wants to grow the top back out slightly but maintain a short nape for an event in June, without it looking too masculine.  After June she will return to a short & spikey do for the summer.

http://www.imagestation.com/album/?id=2129009753 - http://www.imagestation.com/album/?id=2129009753

Any suggestions for style inspiration would be welcomed & also which of her recent lengths and colours suits her best (as she has been many shades of blonde, red and brunnette over the last ten or so years).

IMO, she looked better with the red-brownish colour of the first picture (long hair).

Whatever she prefers about the length is up to her, but I'd advise against exposing her forehead like in the short styles.  Soft bangs (style pic 1 again) look a lot better - other glasses might help too.

Should you've asked to choose fromthe pictures I'd say: go back to where you came from (long), the best picture in there.

I would suggest a shorter nape, as the length there only makes her neck seem shorter.