Agree with the Waterstones - or indeed any bookstore. Not sure in the current climate Waterstones will be looking to open any new stores, sadly.
An upmarket Wine Bar or Public House would be good, planning was turned down for the one in the Close. There is KS but I have not been in there yet - but I mean something large, light and airy. There are options for Coffee in Warminster but people do like brands so a Costa or Starbucks would do well in Warminster.
Might be somewhat controversial but what about a decent technology shop now that Dixons has gone? Argos, yes, of course, but it isn't the same as getting decent advice.
However all of the above would work much better with a more sensible car parking strategy in Warminster!
I'd like to see a much larger Smiths, a Marks and Spencers, a Waterstones (why not, we're getting a Waitrose aren't we), a Starbucks and a McDonalds. Another/better shoe shop as well. There is no "oompf" to the high street anymore. The town needs life and investment - big brands can do this.