2.5 times around the Kinnersley circuit would be a good testing 25 plenty of options for the start & finish areas with a cut through for the time keeprs also
Dave's 25 course is good idea, definitely a gap in our calendar.
A couple of other ideas to throw into the pot, stolen from Hereford Wheelers calendar:
Make the first 10 of the season a road bike event, no tribars or other aero bits. 3 x 2 mile sprints event (course tbc, possibly Kempsey-Severn Stoke, Broadheath or even Stourport?) with points for fastest individual rep, fastest average and most consistent.
There has already been an idea posted for a 25 course for 2012 as suggested by Dave Preece. If others have ideas for the club time trials, be they new courses or the frequency of particular events then please put ideas here.